Preheat the oven to 400F. Turn a nonstick ovenproof skillet to medium-high and add the chorizo. Cook the chorizo for about 7 minutes, breaking it up with a spoon as you go, until it's crumbly and browned. Remove the chorizo to a plate.

To the same skillet, in the chorizo drippings, add the bell pepper, onion, garlic, smoked paprika, and a sprinkle of salt. Cook the veggies for 5 minutes until they have softened, then remove them to rest with the chorizo.

In the same skillet (turn the heat to medium if the pan is very hot or smoky), drizzle the olive oil all over. Layer the potatoes in one layer, slightly overlapping, all over the bottom of the skillet. Sprinkle the potatoes with salt and pepper. Cover the potatoes with the veggies, chorizo, and the cheese.

Crack all the eggs in a bowl and whisk with a fork; sprinkle salt and pepper into the eggs. Pour the egg mixture over the skillet, shaking if needed for the egg to evenly distribute.

Transfer the whole pan to the oven and bake for 20-30 minutes until the egg is no longer jiggly in the center. Very carefully transfer the frittata out of the skillet (I flip mine upside down so the potatoes are on top), and sprinkle with the tomato and scallion. Cut into wedges and serve.