How can I tell someone that I don't like certain food items ?

I’ve been staying with my mom alot since dad passed away, and she likes to cook for me. She makes an alright Hamburger steak but I don’t like it, even though she thinks I do. Truth is, it makes me gag / heave.

This was never a problem when we had a dog under the table, but now, I mostly sneak and throw it into the bushes.

I also frequently am offered food from people that I would never eat because they have perishable items that probably were not stored right, and their houses are messy with dingledobs hanging from the roof of the microwave and gafoontites hanging from the ceiling, and roaches everywhere.

I am not being ungrateful—its just that I cannot stomach certain things.

How do I tell my mom, for starters, that I don’t like hamburger steak—after she has gone to such effort and expense?