I'm actually having a hard time trying to figure out what I cook that DOES have "diet" ingredients in them.
Veggies, veggies and more veggies - spaghetti squash, butternut squash, cauliflower, spinach, zucchini, carrots, mushrooms, broccoli, brussel sprouts, asparagus - roasted, grilled, broiled, sauteed, etc. Seasoned with garlic, thyme, parsley, onions, basil, rosemary, pepper, oregano, cumin, chilli powder, lemon etc. Not a "diet" ingredient in there.
Chicken, fish, turkey - roasted, grilled, sauteed, broiled, baked - with all different herbs, chicken broth, wine, lemon, etc... No diet ingredients here either.
Salads - romaine, spinach, cukes, tomatoes, onions, avocado, bell peppers, etc... served with balsamic vinegar, sprinkled with slivered almonds.
Chilli, soup, stews........
Cooking light.com is a great website for lots of recipes and ideas. You can also just do a google search on, say, "Healthy Cooking" and I'm sure tons of sites will come up.
I'd have to agree that a bit of imagination is required. The possibilities are limitless. Do some experimenting. Have fun with it.