Onion Slimy on the Inside?

Fresh onions are firm and smooth. If your onion or other vegetable feels soft, squishy, or slimy, it is beginning to turn. Finally, fresh onions emit an onion smell, while bad onions emit a foul or rotten odor.

How can you tell when an onion is bad?

Spoiled onions may develop dark spots, which will eventually begin to grow mold. You'll also want to avoid onions that have started sprouting, as this indicates they're beginning to go bad. You can also feel your onions to check how fresh they are. Onions with soft or mushy spots are starting to go bad.

Why is the inside of my green onion slimy?

The older (more mature) green onions tend to accumulate a slimy mucus like coating on the internal wall as they get larger in size.