Zest Bakery & Gluten-free Grapefruit Bars

Zest Bakery owners: Charissa & Patrick Luke

An amazing, and encouraging, trait of American culture is its support of entrepreneurs. If you have an idea, a passion or a dream, the odds are pretty good that you’ll get a chance to realize them, no matter how daunting it seems at the onset. Just look at this farmer, the women behind this restaurant and Patrick and Charissa Luke who started Zest Bakery last July with the goal of bringing organic gluten-free breads, pastries and desserts to their hometown of San Carlos.

“I was hungry. I needed to eat!!” jested Patrick, explaining his motivation for this project. “When I was diagnosed with Celiac disease six years ago and went on a gluten-free diet, it was practically impossible to find any wheat or soy-free crackers, cereals or pasta, unlike the abundance we have today.”

Getting laid off from his Silicon Valley job in September 2009 offered the perfect opportunity to bring his bakery idea to reality. “I’m a believer that when the time is right for a project to happen, things will naturally fall in place.”

Zest Bakery, San Carlos CA

And they did. With Charissa’s sister and cousin lending a hand, the Zest storefront and kitchen was up and running in a mere six months and five days. Yellow walls and abundant daylight streaming in through the front and side windows turn the store into a giant lightbox, accentuated with refurbished chairs and furniture in the colors of the bakery’s logo.

“Opening a bakery has always been Patrick’s dream, and the dream I didn’t know I had,” shared Charissa.

“As someone with Celiac disease, it hasn’t been easy for the most part to find gluten-free foods and ingredients in the Bay Area. Eating out always bore the risk of triggering Patrick’s allergies. Having our own gluten-free kitchen means that we don’t have to worry about contamination risks from gluten-based products. Even the tiniest microbe of wheat or soy can trigger a nasty allergic reaction.”

Gluten-free muffins

Zest Bakery, San Carlos CA

About 80 percent of the bakery’s ingredients are organic and sourced from local businesses and farmers where possible. Their brownies feature Guittard Chocolate and eggs from Clover Organics. Greenleaf purveyors and local Farmers’ Markets provide the fruits featured in their Blood Orange or Raspberry Chocolate muffins.  Spice Hound in Sunnyvale provides the cinnamon for their apple pies and ground ginger in their triple ginger cookies.

All recipes are developed in-house. “Gluten-free recipe development is a steep learning curve,” said Charissa who develops Zest’s dessert and pastry menu. “I needed to understand the properties of the different flours we used and how they worked together, so there were lots of experimenting and testing going on, as you can imagine.”

“The more recipes I developed though, the easier it became. My philosophy is to keep things simple and do direct substitutions for any gluten ingredients,” she shared. “I’m enjoying the process so much now that I wake up in the middle of the night with recipe ideas and can’t go back to sleep until I’ve sent a note to our kitchen manager about it!”

Behind the scenes at Zest Bakery

On a sunny Saturday in January, I accompanied Charissa to the College of San Mateo Farmers’ Market for a day of “recipe R&D”. As a planner who needs to know what I’m going to cook and shops according to a list and less by inspiration, I was excited to observe an inspired shopper in action.

“Every visit to the Farmers’ Market is an R&D session of sorts. Even if we don’t buy anything, seeing the fruits and vegetables in season always sets me thinking about new flavor combinations and items for our menu. Besides gluten-free treats, we also offer vegan and nut-free items as we develop them, so there are many possibilities to experiment with,” said Charissa.

“We’re slowly expanding our menu to not only cater to the gluten-free demographic, but also to people on a vegan diet, or who have nut and dairy allergies,” Patrick said. “Ultimately, we hope to grow our wholesale business and supply local grocery stores like Draeger’s and Sigona’s Markets, and perhaps, other retail spaces in the Bay Area.”

Vince Bernard citrus farmer

Farmers' Market

We stopped at Vince Bernard’s citrus stall with his stunning assortment of limes, grapefruit, tangerines, clementines, meyer lemons and avocados. A few samples were offered and taken, a couple of clementines and grapefruits were scrutinized for blemishes, Charissa, all the while running through her mental list of citrus fruit recipes as she touched, weighed and sniffed out the grapefruits that would eventually end up as Triple Grapefruit Bars.

“How do you do that?” I asked, fascinated.

“I don’t know”, she laughed. “I guess it helps to have a good knowledge of different base recipes (for crusts, cakes or muffins) that you can adjust based on what you have on hand”.

Clearly, I need to bake more often!

Ravioli cutters

Gluten-free ravioli

Gluten-free ravioli

Back at the kitchen, her sister, Cindi of the AntiCupcake Company (whose cheesecakes are also sold at Zest), was preparing batches of Portobello Mushroom and Butternut Squash ravioli that sell out almost as soon as they leave the kitchen, snapped up by Zest Bakery’s regulars, Celiac and non-Celiac alike.

“Most of our regular customers have Celiac Disease, but we’ve also had gluten-tolerant customers tell us about the benefits they’re seeing from switching to a gluten-free diet,” said Patrick. “I’m not surprised by this, because research has shown that our bodies have difficulties processing wheat. When we eat gluten-based foods, our digestive systems have to expend more energy to break it down. Going gluten-free means relieving your body of all that extra ‘work’, freeing up energy in the process and making you more alert as a result.”

As a testament to the quality of Zest’s products, the rave reviews from customers and the local press keep coming in, particularly after their front-page mention in local section of the San Jose Mercury News. The grapefruit bars we shared that day were as delicious and tasty as any regular bar would be, except that its crust had a significantly lighter texture compared with your standard gluten-based version.

Gluten-free triple grapefruit bars

From one man’s idea into a business catering to a part of the Bay Area’s Celiac population, Patrick and Charissa’s enthusiasm for producing high-quality, healthy baked treats that taste just as good (if not better than) the original is infectious, and fast converting a non-Celiac like me to the benefits and possibilities of a gluten-free diet. To get you started, Charissa’s kindly shared their recipe for grapefruit bars below. Happy baking!


Triple Grapefruit Bars (courtesy of Zest Bakery)
Makes one 13 x 9 inch block

Oro Blanco, Ruby Red and Cocktail are just some varieties of grapefruit you may want to use for this recipe. We like to use Pamela’s gluten-free flour blend, but you can also use your personal favorite. Just be sure to check its contents for xanthan gum and omit the ¼ teaspoon called for in the recipe if your flour blend already contains it.

1¾ cups of your favorite gluten-free flour blend
¼ tsp xanthan gum
½ cup confectioners’ sugar, sifted
1 cup butter, chopped and chilled
2 tablespoons grapefruit zest
¾ cup grapefruit juice
4 eggs
¼ cup whole or almond milk
1 cup granulated sugar
½ tsp baking powder

Prepare the crust:

1. In a large bowl, combine the flour and xantham gum (if needed) and stir in the confectioners’ sugar. Cut in the butter with a pastry cutter until mixture is crumbly. Press evenly into bottom of a 13 x 9 x 2-inch baking pan lined with parchment paper. Refrigerate for 20 minutes.

2. Preheat the oven to 325 F, then bake 20 minutes, or until lightly browned.

3. Set aside to cool while you prepare the filling.


1. Zest and then juice the grapefruits. Set aside.

2. Whisk together the eggs, milk, granulated sugar, and baking powder. Add grapefruit juice and zest. Mix until just combined then pour into baking pan.

3. Bake at 325 degrees F for 20 minutes or until center feels firm. Let cool for 30 minutes before slicing.

4. Best served IMMEDIATELY, but can be stored in the refrigerator for up to 3 days.

Inside the Zest Bakery Kitchen

Zest Bakery
1224 Arroyo Ave
San Carlos, CA 94070
650-241-ZEST (650-241-9378)

Open Tues-Fri, 8am-6pm, Sat-Sun, 8am-2pm. Closed Mondays.


  1. I’m having a hard time stopping on this page to leave a comment– I just want to keep scrolling!

    I love the way these bars sound. I’m sending the link to my friend too.

    About the newer post, this is one of those few times, also, that I’m wishing we had some real seasonal vegetables around here (in Hawaii), rather than the same all year round!

  2. Danielle

    @Annelies: What are you waiting for, visit them already! :p Their muffins and sweet treats are totally worth the drive. Plus, they’ve been on a roll with donuts lately, I bet they’re fabulous.

    @Mariko: Thanks for sharing! I grew up in a tropical climate too so I know how you feel, although now that we have to live with the seasons, I miss the year-round abundance that you guys have!

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