For the meatballs I pureed:
half a huge onion
1 giant carrot
a big leaf of kale
Added that to 2 pounds of ground beef with some salt and pepper. Mixed it all up and formed meatballs to fill a 13x9 pan and smothered them with gravy. Baked at 375 degrees for 30 minutes then turned up the oven to 400 for about 10 minutes to help reduce the amount of liquid.
You could also simmer these in a pan to "boil" then for Stage 1-3 although they are "boiling" in the oven.
Gravy was made by simmering beef broth with 3 large, sliced onions until soft. Pureed them and let it simmer for an hour or so until it thickened. Seasoned with salt and pepper.
We served it with fauxtatoes. It would also be good with steamed/sauteed veggies.
My kids love these meatballs (with or without the gravy) - I need to make large batches and freeze them to make quick meals.