There’s an easy way to play with summer’s bounty of fresh fruit and produce. Alicia Walter, co-owner and chef at Once Upon A Tart in New York City often turns to a trusty favorite: tarts.

“Tarts can be so versatile,” Ms. Walter says. “It’s about freshness and spontaneity. I love going to the market and seeing what’s there, maybe it’s a mountain of snap peas at the beginning or asparagus at the end,” and then working what’s freshest into tarts.

Ms. Walter says tarts can make an ideal meal when it is warm. The tart “should offer a meal that’s substantial enough to soak up a glass of rosé but also leave enough room so you don’t feel so bogged down that you can’t go for a swim afterward or keep eating at a long picnic,” says Ms. Walter, who was head chef at La Scuola di Eataly in New York City and chef of private dining at Vetri Ristorante in Philadelphia before joining with her husband, Michael Stern, on Once Upon A Tart in 2015.

For savory tarts, Ms. Walter says it is easy to get creative. “Keep two components the same and then change the third, so you have the great tart shell, a layer of seasoned ricotta on top of that, and then whatever’s in the market that’s fresh and catches my fancy, just quickly saute it and put it on top,” she says.

There are some vegetable combinations that go particularly well together. One of Ms. Walter’s favorites combines baby zucchini or summer squash with caramelized onions and a cornmeal crust as a base. Or pair sliced heirloom tomatoes with a couple of handfuls of grated Swiss cheese and a little mustard on a tart shell, then mix a beaten egg with two tablespoons of heavy cream and a little salt and pour that over the tomatoes, she says. “When it comes out of the oven, it’s just glorious—that cheese has bubbled up and the tomatoes still have their brightness,” says Ms. Walter.

MORE TRICKS OF THE TRADE

With savory tarts, Ms. Walter likes to layer on complex flavors. “Olive tapenade or pesto or mustard are great add-ons. Those all just elevate the tart,” she says. “Or if you’re doing a cornmeal tart, if you toast the cornmeal, you bring out extra flavor in it.”

Fish is particularly summer tart-friendly. Ms. Walter likes to pair fresh salmon with a smoked whitefish purée and herbs like chervil and dill, wrap that up in a short crust and bake it. “It’s great for the summer because it feels light,” she says, adding that she likes to serve it with a cucumber, tomato and caper salad on the side. “You can serve it at room temperature or slightly chilled. Make it a day ahead and keep it in the refrigerator then just slice it and serve.”

Sometimes, Ms. Walter uses summer tarts as a way to “clean out the pantry.” If throwing a summer soiree, she may make minitart shells three to four days ahead, store them in tightly covered containers and then look in her fridge and pantry on the day of the party to see what she can fill them with. “You can take anything like turnip greens, spinach, mushrooms or heirloom tomatoes with a basil pesto and put them in a tart shell. Or, take some olive oil-poached tuna, chop it and lightly saute it and tuck it in the tart on top of some shaved zucchini.”

With fruit tarts, Ms. Walter likes to think beyond the standard blueberry or strawberry custard. One way is to work alcohol into the fruit toppings. “I’m always thinking of how I can use different liqueurs or even wines to enhance the flavor of the fruit,” she says. She’ll either macerate the fruit in the alcohol or reduce the alcohol by cooking it off a little and making a syrup with which you can mix the fruit.

“For me, rosé (wine) and strawberries are best friends, and so are grapefruit and rosé,” Ms. Walter adds. “Or kirsch and some of the stone fruits go really well together. It deepens that winey flavor to them.”

Sometimes the trick is to introduce unexpected ingredients into the combination. This can feature candied kumquats as an accent to a roasted rhubarb tart, or a mixture of blueberries and camomile. “When I close my eyes and imagine blueberries and camomile, I wouldn’t think to put them in the same box based on the flavors. But they’re a perfect combination,” says Ms. Walter. She will steep a camomile plant in simple syrup and add blueberries and let them soak up the flavor. “The blueberries are a little tart and the camomile is grassy and herby so when you put them together with the sweetness, it’s the perfect package.”

FIVE TIPS

• For savory tarts, an easy formula is to start with a basic crust, top with ricotta filling and then add lightly sauteed vegetables on top.
• Try adding layers of complexity by spreading on mustard, olive tapenade or pesto underneath the toppings.
• Macerate or soak summer fruit in wine or liqueurs to enhance the flavor of the filling.
• Avoid too buttery crusts if the tart is being transported or will sit out in the heat; sturdy cornmeal crusts will work better.
• Brushing on egg wash (for savory tarts) or apricot glaze (for sweet) before baking will make the tart look more professional.

Nostalgia can be a powerful thing in summer tarts. Ms. Walter likes to do a s’mores tart with a graham cracker crust base topped with smooth dark chocolate filling and smoky bourbon marshmallows. “It travels well because it has that sturdy crust and sturdy filling,” she says. “And it’s fun because it brings back memories of sitting around a campfire, but this is a grown-up version.”

Regardless of filling, the type of crust is important. Ms. Walter says buttery crusts such as Pâte Sucrée work well with summer flavors but don’t fare well in the heat. “If you’re going to be traveling with the tart in your back seat, stay away from all butter crusts.” Cornmeal crusts are “very sturdy, very forgiving.”

When serving savory tarts at home, Ms. Walter likes to make them a day ahead. “Take them out of the refrigerator half an hour in advance or pop them in the oven just for a few minutes at 300 degrees to warm them through, then you can decorate them with herbs or freshly shaved cheese,” she says.

With sweet tarts, Ms. Walter makes the shell a few days ahead and assembles them just before guests arrive. “Scoop some jam inside of them and add those macerated berries in rosé and put a little whipped cream on top. Or you can use lemon curd or crushed almonds as a base. Those can be built right before your party starts.”

Presentation matters. Ms. Walter encourages home cooks not to overlook an important final step when assembling a tart, especially one that’s covered. “Never underestimate the importance of an egg wash or an apricot glaze” that’s brushed on right before the tart is baked, she says. “It takes it from looking homemade to looking really professional.”