I have to agree with the crockpot idea. Crockpots are cheap (no, seriously cheap) and you can just toss a piece of meat in them with a little broth and some spices (whatever you want), then set it to "low" before you head out the door to work. Come back at the end of the day and it's super tender meat with no work. Cook some extra and there's lunch for a couple of days.
Another one I rely on a lot is just cooking up a hamburger patty (grill, pan, whatever is easy) and topping it with a fried egg or two. Super simple and really good.
Another one (if you're eating dairy) - season a boneless chicken breast and cook it in the oven at 350F. When it's done (165F - I use a probe that has a lead out the oven door - also super cheap and keeps me from screwing up), put a slice of provolone cheese on it and put it back in the oven for a minute or two. While the cheese is melting, slice an avocado, then take the chicken out of the oven and cover it with the avocado slices. It's actually more complicated to explain than it is to just do it, and it's my (non-Primal) boyfriend's favorite dish.