Clean the rockfish and cut into pieces. Finely chop the shallots, garlic, and chili peppers. In a bowl, mix all the seasonings until well combined. Save the tail for soup, and use the rest of the fish. Lightly fry the fish pieces in a pan, then remove them. In the same pan, sauté the shallots, garlic, and chili peppers until fragrant.

Pour the fish sauce mixture into the pan and bring to a boil. Taste and adjust seasoning as needed. Add the fish pieces back to the pan and simmer on low heat, turning the fish occasionally so it absorbs the sauce. Transfer the fish to a clay pot or small pot and continue to simmer on low heat.

When the sauce has thickened and reduced, turn off the heat. Add sliced chili peppers and black pepper. Serve hot or cold with steamed rice and cucumber.