Anchored in a bed of nutty pesto, jammy caramelized onions, and salty feta, a bounty of fresh cherry tomatoes completes this simply perfect bite. Perfect as a hearty appetizer or a light summer meal.
To caramelize the onions in a skillet, first peel and slice the onions about ⅛"-¼" inch thick, root to stem.
Melt 2 tablespoons of salted butter in a large heavy skillet over MEDIUM heat. Add sliced onions and continue to cook, stirring occasionally, until onions start becoming translucent.
Reduce the heat to MEDIUM-LOW, and continue to cook the onions, stirring occasionally for 40-50 minutes, or until they are soft, almost jammy, and rich brown in color. Remove from the heat and set them aside.
Preheat oven to 450°F (235°C) for metal tart pan or pie plate. [Glass pie dish - 425° F (220°C)]
Lay the pie crust into a shallow pie dish or tart pan. Crimp or trim edges. For flakier pastry, place the prepared tart shell in the freezer for 10 minutes before proceeding.
Spread pesto over the bottom of the cold tart shell. Layer on caramelized onions. Add tomatoes and feta to completely cover the onions.
Place prepared tart into preheated oven and bake 20 minutes, checking crust edges after 15 minutes. If the crust is browning too quickly, cover it with a strip of aluminum foil or a pie shield before you return it to the oven.The tart is done when the cherry tomatoes begin to burst and the crust is a light golden brown.
Remove tart from oven and allow to rest 10 minutes. Just before serving, sprinkle with a chiffonade of fresh spinach, fresh basil, and/or arugula.
Notes
Store leftover tomato tart in an airtight container or wrap it tightly in plastic wrap to prevent it from drying out in the refrigerator.Moisture can affect the crust and make it soggy. To prevent this, place a paper towel between the tart and the storage container to absorb excess moisture.Properly store, this tomato onion tart can last up to 4 days in the refrigerator. We do not recommend freezing this tart.