Combine 2 tablespoons of the chilli sauce, the oil, Tabasco sauce, lemon zest, garlic, pepper and a pinch of salt in a shallow bowl. Add the poussins, turn to coat, then cover and refrigerate for 1 hour.
Meanwhile, combine the remaining chilli sauce, the vinegar, capsicum and celery in a medium bowl. Put aside.
Preheat the griller. Reserving the marinade, grill the birds, breast-side-down, 15 cm from the heat for 8 minutes; brush with the reserved marinade as they cook. Turn the birds over and brush with the marinade. Grill for 6 minutes or until they are just cooked through. Serve with the capsicum and celery relish.
Did you know?
One American study found that no significant fat is transferred from the skin to the meat when chicken is cooked. So when roasting or grilling chicken, it's okay to leave the skin on during cooking as long as you remove it before eating.