It is very common for autistics to have ritualized and methodical eating habits. To have a limited range of things they like to eat. To eat the same things regularly.
It is all about order and consistency.
I am like this! I can eat the same thing for breakfast all the time. The same applies for lunch and then dinner. To clarify, not the same food for all three meals, but the same food for breakfast, the same food for lunch and the same dinner repeatedly. I do the same thing when I go out to a restaurant. I order the same thing all the time because I know that I like it.