- 2 tablespoons unsalted butter
- 3 tablespoons extra-virgin olive oil
- 2 medium onions, halved and thinly sliced
- 8 to 10 garlic cloves, to taste, chopped
- 6 to 8 medium waxy potatoes, to taste, peeled and cut into large cubes
- Salt and freshly ground black pepper to taste
- 2 1/2 to 3 pounds grey mullet or whiting, cleaned and gutted
- Juice of 1 lemon
- 3 tablespoons chopped fresh flat-leaf parsley for garnish
- Heat the butter and 1 tablespoon of the olive oil together in a large stewing pot or Dutch oven. Add the onions and garlic and cook over medium-low heat, stirring, until softened, about 5 minutes. Add the potatoes, season with salt and pepper, and cook, stirring gently, until the potatoes are about half cooked, 10 to 12 minutes.
- Place the fish in the pot over the potatoes, drizzle with the remaining 2 tablespoons olive oil, and add enough water just to cover the fish. Season with salt and pepper. Place the lid partially over the pot and simmer over medium-low heat until the fish is flaky and the liquid almost gone, about 20 minutes. Adjust the seasoning, pour in the lemon juice, and garnish with chopped parsley. Serve hot.