、。
Roux is made by sauteing butter and flour together.
Literal
Roux [topic-は], butter [and-と] flour [object-を] sauteing-while make.
ルー (from French 'roux') is the standard Japanese word for the butter-flour base used in curry, stew, and cream sauces. 炒めながら ('while sauteing') uses ~ながら for simultaneous action — you stir as you cook. Japanese curry culture makes ルー a very familiar loanword, though most people buy it pre-made in blocks.