Well, I am by no means a nutrition analyst, but I would think a basic low fat, complex carbohydrate and high protein diet would be good. Obviously the low fat as you are trying to lose a bit of weight. But since it isn't a vital issue as you don't want to be skinny, you could cheat a little. I am starting my attempt to lose weight, but I can't cheat because I have a long road ahead.
The complex carbs take more time for your body to process. The problem with carbs is too much of them will wind up turning to fat. The beauty of the complex carbs is your body is burning them while breaking them down. The basic carbs don't take as much effort to break down, so any extra gets stored.
Protein is, of course, the key to building muscle. Sounds like you have a decent set of muscles based on your saying you want to get cut "again." We all know muscle weighs more than fat. So, get eating protein, get working out, and build muscle along with shaping your body to how you want it to be.
Red meat is a source of protein, but most everyone I have talked to says you should find alternative sources as your primary protein intake. That's my soft spot as I am a big time meat and potatoes kinda guy. Fish, poultry, nuts, and other sources should be primary intakes, but ruling out red meat is not necessarily required.
The problem with red meat is that many cuts have fat marbled into the cut, not allowing you to trim the fat as you do when the fat is on the edge of the steak. I was reading an atricle in
Men's Health that said the leanest cuts of red meat are those with the word "loin" in them. Based on my love of eating red meat, and looking for various good cuts of meat, I've found this to be quite accurate (but this conclusion is simply from observation, and nothing scientific about it).
I know I rambled here, and I apologize. I do believe your best diet is low fat, complex carb, and high protein.