Start the potatoes: Heat the oven to 425°F with a rack in the middle. Line a sheet pan with parchment or lightly oil it so the potatoes do not stick.

Put the baby potatoes on the sheet pan. Add 1 tablespoon olive oil, the dried oregano, 1/2 teaspoon of the salt, and a few grinds of black pepper, then toss until the potatoes are coated.

Spread the potatoes cut side down as much as you can. Roast them for 15 minutes.

Turn the potatoes with a spatula. Roast them for 10 to 15 minutes more, until they are browned on the edges and a fork slides into the middle easily.

Drain the tomatoes: While the potatoes roast, put the chopped tomatoes in a colander set in the sink. Sprinkle them with 1/2 teaspoon of the salt and let them drain for 10 minutes.

Put the Greek yogurt in a small bowl. Stir in 1 tablespoon of the lemon juice, about half of the lemon zest, and a small pinch of salt, then set the bowl aside.

Make the batter: Crack the eggs into a large mixing bowl. Beat them with a fork until the yolks and whites are fully blended.

Pick up the drained tomatoes by handfuls and squeeze them gently over the sink to remove more liquid. Add the squeezed tomatoes to the bowl with the eggs.

Add the red onion, dill, feta, and the remaining lemon zest to the same bowl. Stir to combine.

Sprinkle the flour and baking powder over the bowl. Add the remaining 1/2 teaspoon salt and the black pepper, then stir just until no dry flour remains. The batter should look thick and spoonable, not loose like pancake batter.

Fry the fritters: Set a large nonstick skillet over medium heat. Add 2 tablespoons of the olive oil and let it heat until the surface looks loose and shiny.

Stir the batter once, then scoop scant 1/4-cup mounds into the skillet, leaving space between them. Flatten each mound lightly with the back of the spoon and cook for 3 to 4 minutes, until the bottoms are deep golden and the edges look set.