There are no hard and fast rules as to what vegetables can be used for making pasta primavera. Personally, I prefer a combination of tomatoes, eggplants, bell peppers and carrots. I also like to add fresh basil because it goes so well with garlic and olive oil. In the past, I often added sardines in jars or canned tuna to what traditionally is a vegetable dish, but never fresh seafood. I never realized the difference it makes. The cubes of fresh tuna retained their shape, added flavor to the dish that did not have that overpowering fishy taste one gets from fish in cans and jars.