can i marinate tofu in just soy sauce

basically the title

i have two blocks of tofu, one firm and one extra firm, that i’ve already pressed, cubed, froze, then defrosted in the fridge. i don’t really know how to make a good marinade with what i have lol. would mustard or ketchup be gross to put in the marinade with as long i add seasoning? or can i honestly just soak the tofu alone in soy sauce?

i do have corn starch though