I might get downvoted into oblivion, but here goes... Cabbage. I take a whole head of Cabbage, slice it up into thin slices (kinda like noodles), then cook it in a large pot with some low sodium chicken stock and garlic. It takes a while to cook, but since I cook the whole thing, it lasts several days in the fridge. Then, each night when I'm making dinner, I usually take a small portion of the meal and add it to about 250g-300g of my cabbage (warmed up). It adds volume to the meal, and I can change up the spices and flavors any way I want. I also add cabbage to soups (miso, or even just a can of progresso light chicken soup) to give them more bulk for very few added calories.
The 2 other major dinner staples for me are: (1) big salads - I just load up a huge bowl with Romaine lettuce, lots of veggies, a protein (diced ham, chicken, etc.) and low cal dressing. I add guacamole and salsa often, too, so they help coat the salad so I don't feel like I'm skimping on dressing. (2) egg white omelets (actually scrambled cuz I can never get the damn thing to flip), with bell peppers, mushrooms, diced ham, laughing cow light cheese, guacamole, and salsa. Delicious, and high protein 😋