Resurrecting this thread:
I was SO about to suggest lentils, even before I saw your note about him wanting to eat more lentils. Lentil soup always freezes well, esp. if pureed or semi-pureed; I use old yogurt quart containers, with some plastic wrap on top of the soup for extra protection from freezer burn. Some of my favorite recipes:
http://allrecipes.com/Recipe/Moroccan-Lentil-Soup/Detail.aspx - beans add filling
http://allrecipes.com/Recipe/Vegan-Red-Lentil-Soup/Detail.aspx - superb
http://allrecipes.com/Recipe/Lentil-and-Sausage-Soup/Detail.aspx - a little meaty
Hope this helps!