Kosoto-gari

Also called minor outer reap

The small outside reap behind their heel — the step backward they were about to take, taken for them.

OfficialKodokan — 小外刈 & 小外掛 / Ko-soto-gari & Ko-soto-gake

Canon: the Kodokan 100 (68 nage-waza, 32 katame-waza; IJF/Kodokan classification) · Daigo, Kodokan Judo Throwing Techniques · Kashiwazaki