ぎょうざの具のあまりは？餃子を家で作りましたが、皮が少なかったせいか、具が少し余ってしまいました。

？、、。

What about the leftover gyoza filling? I made gyoza at home, but maybe because I didn't have enough wrappers, I ended up with filling left over.

Literal

Gyoza [gen-の] filling [gen-の] leftover [topic-は]? Gyoza [obj-を] home [at-で] made [but-が], wrapper [subj-が] few [fault-せいか], filling [subj-が] little left-over [regret-てしまいました].

具 'filling / ingredients' is the standard word for what goes inside dumplings, buns, etc. 皮 'skin / wrapper' — the gyoza dough wrapper. せいか 'perhaps because of / maybe due to' adds uncertainty about the cause. ~てしまいました marks the outcome as unfortunate. The opening question reads like an online forum post title.