Peel and finely chop the garlic, then place in a large bowl with the aji amarillo paste (or sauce), lime juice and 1 tablespoon of olive oil. Mix well and season generously with sea salt and black pepper.
Slash the duck breast and leg three times with a sharp knife, add to the bowl, then massage the marinade into the duck pieces.
Peel and finely slice the onion, then add to the bowl with the orange juice. Cover with clingfilm and marinate in the fridge for at least 2 hours, preferably longer.
Remove the duck from the fridge and transfer the meat to a plate. Strain the onions through a sieve, saving both the marinating liquid and the onions in separate bowls, and set aside.
Heat the remaining 1 tablespoon of oil in a frying pan over a medium heat, add the duck pieces and sauté for 8 to 10 minutes, or until golden brown. Transfer the duck to a clean plate and set aside.
To the pan, add the marinated onions and cumin, then finely chop and add the coriander. Fry for 5 to 7 minutes, or until the onions are soft.
Stir in the marinating liquid and bring it to the boil, then lower the heat, add the duck and cook for about 30 minutes, or until the meat is tender, turning halfway. Take off the heat.
Peel, destone and roughly chop the avocado, finely chop the coriander leaves and chives, then combine in a bowl with 2 tablespoons of extra virgin olive oil and the lime juice. Season with a little sea salt to taste.
When you’re ready to serve, take the duck pieces, warm or cold, and slice.
Divide the onion mixture between 4 plates, top with a few slices of meat and a handful of the avocado salad. Deseed and finely chop the chilli, then scatter on top with a grating of lime zest, if you like.