Steps
- Heat ½ cup of olive oil in a pot over low heat. Stir in 3 tablespoons of tomato paste and 2 tablespoons of harissa; cook for 3 minutes.
- Add 5 crushed garlic cloves, 1 whole chili pepper, and 6 cups of water. Season with salt and pepper. Boil for 1 minute, then cover and simmer while making the filling.
- Mix 340g of ground beef, 2 finely grated onions, 3 tablespoons of chopped parsley, 85g of grated Gruyère, and 1 tablespoon of ground coriander.
- Add 1 teaspoon of red chili powder, 2 beaten eggs, and 2 tablespoons of cold water. Season with salt and pepper; knead until cohesive.
- Preheat the oven to 350°F / 175°C. Remove the stems, ribs, and seeds from 6 long sweet bull's-horn peppers. Fill with the beef mixture.
- Arrange in a deep 9 × 13in / 23 × 33cm baking dish. Pour over the sauce. Bake for 45-60 minutes, until the peppers are tender and the filling reaches 160°F / 71°C.