When I was a vegetarian, one of my favourite meals was, rice and cheese enchiladas, however to make them more nutritious you could also add refried beans.
A homemade enchilada sauce that I like is, take some passata, tomato puree, add water (most of your sauce should be water, the tomato is there for flavouring, it's not a tomato based sauce), then add cumin, veggie stock cube, chilli powder, paprika (I like smoked, you can use sweet), oregano, pepper, salt, onion and garlic (I use onion and garlic powder). Boil until thickened slightly, you basically want it to coat the back of a spoon an intensify the seasoning. You can add cornflour to thicken. It should be a highly seasoned sauce, it does not have to be spicy.
I then take the flour tortillas, dip it in the sauce until soft, add filling, roll and place in a pan. Do this until you have enough enchiladas. Cover generously with sauce and cheese. Bake until cheese and sauce is all bubbly, I normally do about 20 minutes at 200.