Preheat the oven to 357°F with a rack in the middle setting.
Slice the top and tip off of the three mini sweet peppers. Use your fingers to remove the seeds and ribs from inside. Then slice the peppers into thin rounds.
Slice the tomatoes into thin rings. If you imagine a line drawn from the stem end to the tip of the tomato, you should be slicing across that line.
Set the tomatoes and peppers aside.
In a small bowl combine olive oil, garlic, and shallot with a pinch of salt and pepper.
Take your pastry dough out of the fridge. Roll it out into a square or circle approximately ¼" thick. I like to use a pastry wheel or pizza cutter to give myself straight edges, but you do you.
Transfer the pastry to a parchment or silicone mat lined baking sheet and dock it all over with a fork. This lets steam escape so the puff pastry doesn't bubble up awkwardly when it bakes.
Brush the pastry dough all over with the olive oil mixture, all the way to the edges.
Arrange the peppers and tomatoes in rows, overlapping each other as needed, across the surface of the dough, leaving about ¼" margin all the way around.
Use a microplane to sprinkle lemon zest down across the tart, followed by a generous dusting of parmesan cheese.
Bake at 375°F for 10 minutes, then rotate the sheet pan and bake for another 10-15 minutes, until the edges of the tart are a deep golden brown with lots of flaky layers.
Remove from the oven and let cool on a wire rack. Slice into wedges or squares and serve immediately.