Grilled Maxicana
750 gms halibut fish  
75 gms butter  
2 small onions, chopped  
100 gms mushrooms, sliced  
2 large tomatoes, chopped  
1tbsp tomato puree  
3 tbsps dry wine  
1 large avacado pear, sliced  
8 walnuts, chopped and fried  
salt and pepper to taste