If you have a blender, food processor, or immersion blender you can add beans, lentils, etc and veggies into a red pasta sauce to get your protein and veggies in with keeping a good texture. Just blend up yours beans and veggies (I use frozen stir fry mix but anything works) and add into the sauce as you simmer it for a while. Works well to thicken up a sauce by doing this, so save some pasta water to get the consistency right.
Depending on time I try to simmer my sauce for an hour or two.
If you combine this with whole wheat pasta you have a cheap, healtht, great tasting meal that's vegan friendly (if you don't add cheese at the end). I'm sure this is blasphemy for an Italian, but I love the meal.