Char the peppers, skin them, split them, and remove their core and seeds. Cut them into strips less than an inch wide and 1 1/2 -inch long. You can prepare the peppers early the same day that you are making the fish for dinner.
Turn on the oven to 375°.
Wash the fish in cold water and pat it dry with paper towels.
Coat a baking dish with 2 tablespoons of olive oil. Lay the salmon down in the pan, skin side facing down if you have long fillets. Distribute all around the salmon the peppers, capers, and the whole peeled garlic cloves. Sprinkle with a liberal quantity of salt and freshly ground black pepper. Pour the remaining olive oil over the fish. Put the dish in the preheated oven and cook for 16 minutes. Let it settle for a few minutes before serving.