I generally do:

Scrambled eggs with sharp cheddar (I use heavy cream whipped in), butter, himalayan salt, and nutritional yeast. Sometimes I'll add a meat like ham, sausage, or ground beef. If I do that, I might add a bit of low sugar salsa or just diced tomatoes.

Ham/salami with sharp cheddar, wrapped around pickle spears. Generally I'll have this with a side of something fatty - berries with cream, ranch dip, a bit of mayo, or low carb chocolate mousse.

any leftovers.

Bell pepper strips with pate, topped with microwaved cheese crisps, and either pork rinds with ranch dip, mousse, or something similar...

pizza on a plate - shredded cheese, dotted with tomato sauce, diced tomatoes, or crushed tomatoes. Garlic salt and Italian seasoning blend. Topped with pepperoni, ground beef, or taco meat, then microwaved until the edges are crispy (mimics the crunchy crusts)... Sometimes I'll add a thin bit of cream cheese under it for extra fat.

Copycat Zuppa Toscana soup, without the potatoes. Had a bowl of the Olive Garden's not long ago, even salting it well, I couldn't eat it - mine is so much more flavorful!!

Mississippi Roast...eaten like a veggieless beef stew. Drools.

Made low carb blt's not long ago, lettuce leaves slather with mayo, topped with bacon. Didn't have tomatoes at home, thought it would have been more awesome with it...

Those are most of my defaults... I can think of more ideas if you need them.

This week (I usually do the same thing for a week at a time, and it's my first week on keto) is over easy eggs (3) and 3-5 strips ready to cook bacon. Fast, easy and taste amazing!!

Big Mac salad for me! Leftover burger from last night on bed of lettuce with homemade special sauce!! Yummy!

I'm still full from my BPC this morning, but when I do eat I think it will be a few ounces of my left over pork roast and a salad. I need to work on getting more green veggies in and see if that helps with the bruises I'm getting.

I try make a bunch of chicken breasts in my pressure cooker (can also use slow cooker), with salt, pepper, onion powder, and whatever other seasoning I feel like. And I freeze them individually. So if there isn't leftovers for tomorrow's lunch, I can pull out a chicken piece i froze and make chicken salad, or mix it in a green salad, or add stuff to it like I did today. Today I'm having a Mexican style chicken with avocados, lime wedges, sour cream, tomatoes, and hot sauce.

I made a lettuce wrap today for lunch. Lettuce, tomato, Colby cheese, turkey, ham, pre cooked bacon, mayo, salt and pepper.

My favorites are:
breakfast for lunch. Usually 4 eggs, 2 slices American, bacon and reduced sugar ketchup.
Leftovers.
Salads with leftover meat from the night before.

If I eat lunch it's usually salami and cheese. I drink BPC and sometimes don't eat til dinner. Then I eat until full.

@LauraCoth The secret to that is to put away the "leftover" portion before ever even serving a thing. Put it in a container he can recognize as yours, or hide it in a "brussels sprouts" bag in the freezer or something equally unappealing... It can work if done well.

I have the same thing every day. Solid white albacore tuna, mayonnaise and baby spinach. I put Parmesan cheese whisps on top for texture.