すみません、この唐揚げ、もう少し温めてもらえますか？ — Excuse me, could you warm up this fried chicken a bit more? (Convenience · Store, Formal — to staff, JLPT N4)

Gesture & etiquette

Point to the item (karaage) that you've already picked up or are pointing at in the hot food section.

This usually applies to items from the hot food counter (like karaage, nikuman). They might use a small oven or fryer, not a microwave. Microwaving these items can make them soggy.