Green onions in water on my counter. I've been doing this for a while now and I always have the freshest green onions on hand (doesn't wilt like they would in the fridge) and I haven't had to buy in a while. I just cut off what I need and it grows soooo fast!!!
Also on these boards
Re-grow green onions in water on your windowsill in just 2 weeks! Simply cut off and use the green portion (leaving about 3 inches of the white root portion), then place the roots in a glass or jar and fill with water and place in windowsill. This is the result I got in just under 2 weeks of winter sunlight in my windowsill. Pretty crazy eh? An interesting tip I read about in Cook’s Illustrated. You can actually do it twice with the same onion roots. It works!