My favorite non-meat marinara sauce is:

dice 1 large carrot; 2 sticks celery, 1/2 onion saute till onion is transluscent in olive oil. Add one large can of crushed tomatoes, 2 tablespoons tomato paste, add garlic (I add alot, but do this to your taste) add small amount of dried oregano, thyme, basil Iif you do not have fresh). Simmer for 1 hour. Add chopped fresh basil if you have it and did not add dry) Place in blender and blend (be careful hot liquids in blender are dangerous, place lid on blender and hold down with kitchen towel).

If you want to add the roasted red peppers as in your other recipe, this will change the taste a bit and I like this sometimes, but not always. Just add them whole out of the bottle or if you roasted them yourself, get rid of the seeds. This will also cause the sauce to change color a bit and make it a bit more orange then red.

If you want a little more richness in your sauce, once it is blended, add a bit of cream; but of course, this will turn it a different color as well, but this is nice for a much more rich flavor.