豆腐 is already cooked, just heat them, then u can eat. if u want 豆腐煎金黃色, you have to use {soft} or {smoth} 豆腐 and use the very very very high heat oil to fry them. however u should be careful the steam from the heat oil. u will not take a long time to fry them, just fry them until u see them in golden colour.
If u fried them, u can keep the leftover tofu (completely cool down) in ur refrigerator up to 2-3 days. If ur tofu do not cook, u can use the tape water to cover it and put it in the refrigerator up to 2 days.
u cannot keep 生的蘑菇 fresh, cos they contains a lot of water, they will become dark-brown on the next day. If u want to keep it longer, u have to cook them first, and then u can put into ur refrigerator up to a week. Hope all informations can help you.