Heat 1 tablespoon of oil in a medium saucepan. Add the onions and garlic and cook until soft. Add the chorizo and cook until golden brown. Add the couscous and coat with the mixture. Bring the chicken stock to a boil, pour over the couscous, bring back to the boil, cover and remove from the heat. Let sit 10 minutes. Fluff with fork and let cool. Preheat grill. Stuff the squid with the couscous mixture and secure the end with a toothpick. Brush the squid with the remaining olive oil and season with salt and pepper. Grill for 2 to 3 minutes on each side.