Stir together the juice of one of the limes with the soy sauce, oil, garlic, honey, half the chopped chilli and salt and pepper to season in a shallow dish. Add the chicken and turn to coat. Marinate for at least 30 minutes or overnight in the fridge.
Preheat a moderate grill. Combine the pineapple with the grated zest and juice of the second lime, the red onion, the rest of the chopped chilli and the mint in medium bowl. Season to taste, then set aside.
Lift the chicken from the marinade and place on the grill rack. Grill for 12–15 minutes, turning and basting with the marinade, until the juices run clear when the chicken is pierced with a knife.
Transfer the chicken to a board and cut diagonally into strips. Divide the spinach leaves among four plates, scatter over the tomatoes and arrange the chicken on top. Spoon over the salsa and serve immediately.
You can make salsas with all kinds of different fruits, according to what is in season. Try chopped peaches or mango, or cantaloupe melon sprinkled with lime juice, a little finely chopped stem ginger, if liked, and some chopped fresh mint, basil or coriander.