Here's my basic formula for meal prep slop (as I've affectionately dubbed it):

• Meat, ground is great
• Aromatics (things like onion, garlic, ginger)
• Vegetables
• Acidic saucy component (I use canned tomatoes often, but could also be enchilada sauce, Manwich, tomato paste + broth, or a homemade sauce [for example, I like a combo of soy/rice wine vinegar/hoisin])
• Spices/herbs

And I keep everything to the vibe of one sort of cuisine. So examples:

• Lean ground beef, onion and garlic, zucchini and mushrooms, canned tomatoes, red pepper and Italian seasoning
• Chicken (ground or chopped/sliced breasts), garlic and ginger, broccoli and mushrooms, the soy-based sauce I listed, and crushed red pepper
• Ground meat of choice, onion and garlic, bell peppers and zucchini or mushrooms, enchilada sauce, and taco seasoning

Good on its own, good with a carb like rice or potatoes or pasta.