AARON WOO knows his vegetables. During the rainy, kale-and-potatoes dregs of late winter, he had the confidence to open Natural Selection, his strictly vegetarian restaurant on NE Alberta Street, relying on his deep catalog of techniques to bring the best out of wintered-over fare.

But like many a Portland chef, he breathed a sigh of relief when the soil began to heat up. For a man who can practically dehydrate vegetables, truffle creams, and texture foods in his sleep, he’s happy to let July’s harvest do its own work in simple dishes like this baby squash frittata. “Summer produce sort of highlights itself—you don’t have to fuss too much,” he says.

Woo loves the delicacy of Oregon’s baby squash, from zucchini to pattypan. “They’re more tender, and you don’t get those seed pockets,” he says. Woo pairs the baby squash with two equally savory-yet-subtle cohorts, fresh eggs and creamy fontina; adds caramelized onions for a depth of sweetness; and ties it all together with a dollop of lemony crème fraîche.

Beyond showcasing the squash, Woo’s frittata has another thing in its corner: it’s easy. While he pulls his hellish restaurant shifts, Woo keeps the frittata at the top of his list for entertaining on his days off. “You can make it a day ahead, you can make it the morning of. Even if you incinerate it, you can do up another one really quickly,” he says. “The simplicity of it is awesome.”

Baby Squash Frittata 

Serves 4-6 

• 3 tbsp olive oil, divided 
• 8 baby zucchini or other baby heirloom squash, 3–4 inches long, 4 of them grated and 4 sliced thinly
• 1 medium onion, diced
• 8 eggs
• 2 tsp Dijon mustard
• ¾ cup crème fraîche, divided
• 1 tbsp parsley, chopped
• ¹/³ cup fontina cheese, grated
• Salt and pepper 
• ½ lemon, zested and juiced 

(1) PREHEAT oven to 375 degrees and place a rack in the top third. (2) HEAT a 10-inch cast-iron pan over medium-high heat. (3) ADD 1 tbsp olive oil, then the sliced squash, and sauté for a few minutes to soften. (4) REMOVE squash slices from pan and set aside. (5) ADD the remaining 2 tbsp olive oil, then onion, and sauté until caramelized, reducing heat as needed to cook evenly. (6) WHEN onions are caramelized, add grated squash and sauté another 1–2 minutes until softened. (7) TURN off heat. (8) MIX eggs, mustard, ¼ cup of the crème fraîche, parsley, fontina, and salt and pepper to taste in a bowl. (9) TURN heat to medium-high and pour egg mixture into pan, mixing with a spatula to incorporate the onions and grated squash. (10) LAYER the squash slices over the egg mixture and place in oven until the frittata is browned and puffed up, about 20 minutes. (11) WHILE frittata bakes, stir the remaining ½ cup of crème fraîche with lemon juice and zest in a bowl. (12) REMOVE frittata from oven and serve with a dollop of lemony crème fraîche and a salad to accompany.