帮忙做饭可以说为：Can you help me with cooking? 或者是 Could you lend me a hand with preparing the meal? 如果想要更加礼貌地表达，可以说：Would you mind assisting me in the kitchen? 或者是 May I ask for your help in cooking? 无论怎样表达，都要记得感谢对方的帮助。