Sauté onion in a tbsp of olive oil in a large soup pot over low heat for about 5 minutes.
Add 2 cloves of minced garlic and 2-3 cups of chopped veggies of choice and stir well. Sprinkle with 1/2 tsp of salt and 1 tbsp of Italian seasoning, turn up the heat and saute the veggies for about 5 more minutes. (If you are using a store-bought vegan meat product or seitan sausage you can add it now and saute it with the vegetables. If using my homemade vegan sausage crumbles, do not add them yet.)
Add a 25 oz jar of spaghetti sauce, a 28 oz can of tomatoes, 2 tbsp tomato paste, and 6 cups of water. Then stir well and simmer at medium-high heat until it begins to boil. (Taste the sauce then add 1/2 tsp salt and 1 tbsp of sugar if you choose, adjust to your taste).
Once it boils, add a package of broken lasagna noodles or use any large flat noodles.
Cover and simmer for about 15 minutes (stirring occasionally) until the pasta is soft. Then add 4 cups of rough-cut baby spinach. (Add my homemade vegan sausage crumbles at this time if you are using those and stir well)!
MAKE THE BECHAMEL SAUCE (OR USE VEGAN CHEESE INSTEAD)
Heat 1 1/4 cup plant-based milk in a saucepan or in a glass measuring cup in the microwave until it is warm but not boiling.
Heat 2 tbsp vegan butter in another small saucepan until it melts then sprinkle with 2 tbsp of flour and stir until it gets bubbly
Slowly stir in the hot milk stirring constantly until the sauce is smooth and comes to a slow boil and salt to taste. Add 1 tablespoon of nutritional yeast for a cheesier flavor.
Pour the bechamel over the top of the lasagna soup.
Scoop into bowls and serve hot. Garnish with some fresh parsley or basil.
Notes
If you are using store-bought vegan sausage or beef crumbles, you can cook them at the same time as the vegetables.
If you are using my homemade sausage crumbles, cook them separately and toss them in at the end of cooking. They will lose their flavor and some of the texture if they are boiled in with the lasagna.
Don't continue to simmer the dish after the pasta has cooked, or it will become mushy.