When we first made this, we omitted them. Then, on a second go-round we added a whole jar. Wow, what a difference they made — roasted red peppers add some sweet and a little smokiness. With lots of vegetables including zucchini, summer squash and roasted red peppers the lasagna is flavorful, but not at all heavy. We really do not miss the meat. Add your favorite vegetables to this — mushrooms, spinach or carrots would be great. When you cook the zucchini and squash try not to overcook them — you want them to be tender, not mushy.