grate the zucchini and squeeze as much fluid out of it as possible. (the weight of zucchini is for before this squeezing procedure, though, so weigh the whole zucchinis, then grate and squeeze.)
mix all the ingredients together in a bowl with your hands. make sure it's well incorporated!
form into balls.
at this point, you can either fry them in a pan or bake them - we opted to bake them, and did so for about 20-25 minutes a side at 375. we put them in a glass casserole dish on top of some parchment paper.
dice the tomatoes up in chunks and throw them in a pot with some olive oil.
cook until the skins are softened, then either blend with a submersion blender or toss in a food processor/blender and return to the pot
in a smaller separate pot, melt the butter and then stir in the flour. stir quickly so it incorporates and becomes a smooth golden mixture.
pour this roux into the tomato sauce while whisking.
throw some pasta on to cook at some point during all this, then strain, top with sauce and meatballs and fresh basil and parmesan, if that's your bag.