Ingredients

2 fl oz (50ml) vegetable oil
3 large onions, peeled and roughly chopped
3 garlic cloves, peeled and roughly chopped
5 1/2 oz (150g) pasilla chilies, roughly chopped
2 medium tomatoes, halved
1 tbsp Mexican orégano (or sage mixed with Italian oregano)
3 1/2 fl oz (300ml) fresh orange juice
salt and freshly ground black pepper
1 cooked duck, meat shredded
12 soft corn tortillas
2 large avocados, peeled, pitted, and sliced, to garnish 

Instructions

In a frying pan, heat the oil, and sauté the onion, garlic, and chilies until softened. Add the tomatoes and oregano and cook gently for about 15 minutes, stirring from time to time. Transfer to a food processor and blend to a purée.

Pour into a saucepan, stir in the vinegar and orange juice, and warm over low heat. Mix in the shredded duck meat, season with salt and pepper, and simmer for about 10 minutes.

Heat the tortillas on a griddle or in the oven (they should stay soft, not crisp). Place a tablespoon or two of the duck mixture along the center of each, and fold in the sides to close. Serve garnished with avocado slices.