4 medium green bell peppers, roasted and cut into strips
2 medium red bell peppers, roasted and cut into strips
6 medium tomatoes, peeled and diced (about 3 cups)
2 large Spanish or Vidalia onions, ends trimmed
3 tablespoons olive oil
3 mild chili peppers, stemmed, seeded and cut into thin strips (may substitute with a small red bell pepper)
2 to 4 medium cloves garlic, minced
2 teaspoons sea salt, or more to taste
2 sprigs thyme
1 bay leaf
1/4 to 1/2 teaspoon piment d’Espelette (may substitute Anaheim chili powder or chili powder)
Freshly ground black pepper
Cut the onions in half from top to bottom, then lay each piece cut side down on a cutting board and cut each piece in half again from top to bottom, stopping just short of the root end; cut each onion half crosswise into thin slices; there should be about 4 cups total.
Place a large, high-sided skillet or casserole with a cover over medium heat and add 2 tablespoons of the oil. Warm the oil for a minute, then add the onions and cook, stirring occasionally, for 10 minutes, until the onions have picked up some color. Add the remaining tablespoon of oil to the skillet, then add the strips of peppers and the chilis. Cover and reduce the heat to medium-low; cook for about 20 minutes, stirring frequently. Add the tomatoes, garlic to taste, salt, sugar, thyme, bay leaf, piment d?Espelette and a few grinds of black pepper to the skillet, mixing well to combine. Cover and cook for 10 minutes, then remove the lid and let the piperade cook for 15 minutes, stirring occasionally. There will be a fair amount of liquid. Taste and adjust seasoning with salt, pepper or piment d?Espelette.
The Basque style is to serve this with Bayonne ham and eggs.