That's a shame. What's wrong with them? My parents discovered their tomatoes have blossom end rot, they're pretty bummed. I told them I'll have lots to give them
I've been looking online but it seems you cut the onions up and dry them in either your oven or a food dehydrater. Food dehydrater takes longer but I might do that way, it's too hot to turn the oven on and keep it propped open. Then you grind the dried onions. I bought a spice grinder because I don't want to grind onions in my blender, I use that for protein shakes. Don't want onion flavored protein shakes!