My favourite easy meal is tuna steak with buttery rice. I soak the tuna steak in lime juice, cover it with black pepper, then grill it. Prepare a portion of rice, then melt in a little butter, and season as required. Add a bit of salad on the side if you can be bothered. SO easy, but SO tasty! I'm normally terrible at cooking fish, but I haven't failed at this one yet. :)
Failing that, jacket potato with as much cheese as my arteries will stand. Or nachos. Don't buy a kit, just keep a stock of cheap tortilla chips, salsa, jalapenos, guacamole, etc. Then arrange on the plate, cover in cheese, and microwave for a couple of minutes. Goddamn I could go for some nachos right now...