根据所给材料和提示语，写一篇短文描述怎么制作牛肉三明治。
　　Ingredients(材料):2 pieces of bread; 1 spoon of cheese; 1 green pepper; 1 onion; some mushrooms(蘑菇);2 pieces of beef;2 spoons of relish(开胃小菜/调味品)
　　要求：80词左右