Place the garlic, jalapeño peppers, most of the coriander, 2 tbsp of the lime juice and the vegetable oil in a mini food processor or blender. Process until finely chopped and blended and transfer to a small bowl.
Toss the chicken and fajita seasoning in a bowl with the remaining lime juice. Heat a large, deep non-stick frying pan over a medium-high heat. Add the diced chorizo and fry for 2-3 minutes, stirring, until the fat begins to run from the chorizo. Add the chicken and cook over a high heat for 5 minutes until no longer pink.
Stir in the onion and peppers and continue cooking over a high heat, stirring all the time, for 5-6 minutes until the chicken is cooked through and the onion and peppers are just tender. Season well with freshly ground black pepper.
Serve the fajita mix along with the tortillas, coriander salsa and sour cream. Garnish with lime wedges and the reserved coriander.