当小学生想要用英语写一篇关于做菜的作文时，他们可以遵循以下步骤和结构：

选择主题

可以选择一道自己熟悉且喜欢的菜，如鸡肉三明治、木耳炒猪肉、西红柿炒鸡蛋等。

开头

可以用简单的句子介绍今天要做的菜，例如：“Today, I am going to tell you how to make [菜名].”

准备材料

列出制作这道菜所需的所有材料，例如：“You will need [材料1], [材料2], [材料3], and [材料4].”

步骤描述

按照制作顺序，详细描述每个步骤。例如：

“First, [步骤1].”

“Next, [步骤2].”

“Then, [步骤3].”

“Finally, [步骤4].”

结尾

总结并表达自己对这道菜的喜爱或感受，例如：“I love this dish because [原因].”

Title: How to Make a Chicken Sandwich

Introduction:

Today, I am going to tell you how to make a delicious chicken sandwich.

Materials:

3 slices of bread

Jam

Chicken breast

Cabbage

Salt

Butter

Steps:

1. First, take out the chicken breast and cut it into small pieces.

2. Then, cut the cabbage into thin strips.

3. Heat some butter in a pan and cook the chicken pieces until they are fully cooked.

4. While the chicken is cooking, toast the bread slices until they are golden brown.

5. Spread jam on one side of each bread slice.

6. Place the cooked chicken on one slice of toast and add the cabbage strips.

7. Finally, cover the sandwich with the other slice of toast.

Conclusion:

This chicken sandwich is simple to make and really tasty. I enjoy eating it with a glass of milk in the morning.

通过以上步骤和结构，小学生可以轻松地用英语写出一篇关于做菜的作文。