Store-bought puff pastry makes a quick and easy foundation for these summery, savory tarts. Smarts: Any tomatoes will work for these tarts. Use heirloom, cherry, Roma, or a combination of tomatoes (bonus for using a variety of colors)!
Puff pastry - Thaw according to package instructions. (Can be done 1 day ahead)
Make garlic oil - (If prepping right before cooking, get oven heating before continuing with prep.) Chop garlic. Combine garlic, olive oil, and dried oregano. (Can be done up to 5 days ahead)
Tomatoes / Cucumbers - Prep as directed. Store separately. (Can be done 1 day ahead)
Cucumbers - Whisk together vinegar and mustard. Add cucumbers. Refrigerate for at least 20 minutes and up to a day. (Can be done 1 day ahead)
Dust a countertop with flour. Unfold pastry onto floured surface and roll out into a 12” / 30 cm square (for 4 servings; adjust if customizing). (Note: Using a rolling pin or your palms, gently stretch the pastry into a square.)
Transfer pastry to parchment-lined sheet pan.
Brush garlic oil over top of pastry. Add tomato slices (it is okay if they overlap slightly). Crumble feta cheese on top.
Bake tart until golden brown, 15 to 20 minutes.
While tart bakes, toss cucumbers with mint. Season with some salt and pepper.
Cut tart into slices. Serve with cucumbers on the side. Enjoy!