1. Preheat the oven to 350°F (180°C). Brush 1 filo sheet with oil and cut into quarters. Place a filo quarter in a tartlet pan. Stack the remaining three sheets on top of the first, giving each a quarter turn before stacking. Fold the filo over the edge of the pan. Brush with oil and bake for 10 minutes, until crisp and golden.

2. To make the filling, broil the peppers, skin side up, until the skin is blackened and blistered. Cool. Peel and cut into thick slices.

3. Heat 1 tbsp oil in a frying pan and cook the chorizo until crisp and browned. Drain on paper towels.

4. Arrange the peppers, onion, and cheese on the tarts. Top with hot chorizo to serve.