Sweet and Hot Sauce

Name: Sweet and Hot Sauce (Dabu-Dabu Manis)
Cuisine: Indonesia
Ingredients: 2 tbsp chopped basil leaves; 2 large red chillies, de-seeded and finely sliced; 2 shallots, finely sliced; 2–3 tsp sugar; 2 tbsp kalamansi juice or lime juice; 3 medium tomatoes, skinned and de-seeded, then quartered and thinly sliced; 1 tsp salt