Six nutrients needed by human body: protein, sugar, oil, vitamins, inorganic salts and water; Combined with the meaning of the question, the main component of rice is sugar, and braised fish and spicy tofu contain oil, protein and inorganic salts, indicating that the vitamin content in food is less; Therefore, in order to make the nutritional collocation more reasonable, it is necessary to supplement foods rich in vitamins.

A, stewed beef is rich in protein and oil, the option is wrong.

B, vegetarian fried beans are rich in vitamins, so the option is correct.

C. Egg custard is rich in protein, and the option is wrong.

D. Xiaomi porridge is rich in starch and belongs to sugar. The option is wrong.

So choose B.