Combine meat, rice, onion and salt. Form into 1-2 inch meatballs.
Place in a single layer in a deep baking dish.
Combine soup, water, and Worcestershire sauce.
Pour over meatballs (meatballs should be mostly covered).
Bake covered for 1 1/2 hours at 350 degrees, or until rice is tender. (Takes about an hour if using white long grain rice, takes up to 2 hours if using brown rice). *You may want to stir partway through if meatballs aren’t completely covered, to allow all of the rice to absorb some liquid*.
Note for freezer cooking: Flash freeze raw meatballs. Place in ziploc bag when frozen. Freeze soup mixture separately in another ziploc bag. When ready to cook, thaw both meat and soup (will need to re-stir soup because it separates), then combine into baking pan to bake.