1 Place wooden skewers in water. Rinse chicken breast fillets, pat dry and cut into 2 cm (approximately 3/4-inch) cubes.
2 Halve and squeeze limes. Thread chicken cubes onto the soaked skewers.
3 Combine paprika, cayenne pepper, 3 tablespoons lime juice, tamarind paste and ketchup.
4 Place skewers in a container and cover with plastic wrap. Place in refrigerator to marinate for at least 2 hours.
5 Meanwhile, rinse the tomatoes and cut into quarters, removing stems. Seed tomatoes and cut each quarter in half crosswise.
6 Peel the onion and chop coarsely. Halve chile pepper, remove the seeds, rinse thoroughly and chop finely.
7 Halve avocados and remove the pits. Gently work a spoon between flesh and skin of avocado, removing the fruit. Cut into large cubes.
8 Rinse cilantro, pat dry and chop the leaves. Combine 1 tablespoon lime juice, tomatoes, onion, chile pepper and avocado, and season with salt and pepper.
9 Arrange skewers in a grill pan or on a charcoal grill and cook over medium heat for 7-8 minutes. Serve with avocado and tomato salad.