Melt butter in a large frypan over medium heat. Fry the eggplant in the butter until lightly browned, stirring frequently. Remove from heat, and set aside to cool slightly.
In a large bowl, combine the chilli, tomatoes, onion and eggplant. Mix together the vinegar and oil, pour over the vegetables and toss gently to coat. Cover and chill for at least 3 hours, or overnight. Toss salad with coconut and peanuts just before serving.