。
I accidentally left a tiny bit of food behind.
Literal
Cooking [object-を] a-little left [regrettably-てしまった].
ちょこっと again — 'just a little bit.' 残してしまった uses ~てしまう to express regret over an unintended outcome ('ended up leaving behind'). The sentence captures a common dining scenario — not quite finishing everything — with the regret marker showing the speaker knows food waste is frowned upon.