thin slice; slicing thin
Refers to both the act of slicing something thinly and the resulting thin slices, especially in cooking.
肉を薄切りにして鍋に入れる。
Slice the meat thinly and put it in the pot.
薄
Put thin slices of ham in the sandwich.
薄切り is a native Japanese noun for a thin slice of food, while スライス is the loanword used the same way, often as a suru-verb.
Compound of 薄 (usu-, 'thin') + 切り (kiri, 'cutting'), from the verb 切る (kiru, 'to cut').