"They replace my egg with tofu."
Translation:Mereka mengganti telur saya dengan tahu.
"Sama" means "the same as" or "equals." You could probably get away with using it in a conversation, but it's sort of an awkward construction. "Degan tahu" flows better. I would've said "untuk tahu," which is "for tofu," but I can't recall if the Duo lessons have gotten to "untuk" yet.
(I would also follow this up with, "Dan perang mulai waktu itu" which is "And that's when the fight started." If I didn't order tofu, don't give me tofu unless you want to be wearing it. :)