I (kind of) feel your pain - DH is veggie and I am not and I don't want to cook two meals (or eat separately). I dread what's going to happen when DD and any other DCs grow up ...
Can you do bacon? It is usually enough to give a meal a nice meaty kick and improves almost anything You just need to cut into pieces with kitchen scissors then fry until golden at the edges.
Stuffed peppers - cut peppers in half and remove seeds. Cut up enough tomatoes into big chunks to fill pepper halves. Put a big handful of fresh basil, a couple of cloves of peeled garlic, a tsp or so of capers, salt and pepper and a big glug of olive oil into a handheld blitzer thing and blitz into a puree. Pour over tomatoes in peppers. Roast until browned on the edges and serve with salad/couscous/bread. Scatter with fried bacon pieces for omnivores.
Lentil pasta sauce (can make loads then freeze) - Cook med chopped onion and clove chopped garlic in oil for five minutes until onion is soft. Add 1 1/2 cups brown lentils, whole dried chili, salt and pepper, and 900 ml water. Simmer 30 minutes. Add 2 tsp stock powder, 1/4 tsp dried basil, 1/4 tsp dried oregano, can chopped tomatoes, 140g tomato paste, and vinegar (can't remember what I used - prob balsamic). Simmer for an hour. Add cooked pasta, serve veggies, stir in fried bacon pieces, serve omnivores.
I'm planning on making this for a bunch of veggies following a winter day walk on Christmas Eve, with a couple of cooked sausages on the side for the omnis.
Make a couple of basic tomato sauces: chop up load of onion, carrot and celery and divide between two big pans. Cook for a few min until soft. To one pan add chopped root ginger, turmeric, cumin, maybe some garam marsala, stir and cook for another minute. To other pan add chopped garlic, maybe some fresh herbs and a couple of bay leaves and cook for a minute. To both add a stack of tomatoes (fresh/canned/creamed etc) and good squirt of tomato puree, maybe a glug of red wine and some balsamic vinegar to the one with herbs in. Simmer away for a bit then blitz (or leave chunky if you prefer). Sorry if I'm teaching my grandmother to suck eggs here, but bear with me ... Make loads and freeze in portions.
The one with spices in I generally just heat up and add a tin of pulses and whatever veg we have in eg tonight we had it with chickpeas, petit pois and broccoli on brown rice; also thought that chickpea, spinach and potato (cubed, cooked and fried) would be good too. Or paneer. Anyway, could probably just chuck in some cooked chicken too for the omnis and let it heat through.
Meditarranean-style herby sauce:
- shove in some veg and/or cooked meat (chicken/cooked sliced sausage/bacon pieces) and serve with pasta
- mix in can of kidney beans, chopped mushrooms and cooked chicken for the omnis, roll in tortillas or pancakes and bake
- add veg stock and whichever veg/pulses you have to hand and serve as a chunky soup; for omnis stick in some bacon/sliced sausage/cooked chicken (or poach raw chicken in pieces in the soup for more chickeny flavour)
Think that's all I can think of for the moment - generally these days I eat veggie too or we have the veg and stuff out of the freezer (sausages for me/quorn for him etc) option. Hope that's some use and not just all really obvious stuff you've done already.