Recette facile de ratatouille maison

What does “mijoter” mean in French?

Mijoter is to cook slowly over a low heat, just below a boil: laissez mijoter à feu doux. A plat mijoté is a long-simmered dish. The verb transfers neatly to people, too: qu’est-ce que tu mijotes ? means “what are you plotting?” — the same idea of something developing quietly out of sight, much like English “what are you cooking up?”

Kitchen neighbours: mitonner (to prepare lovingly), faire revenir (to brown), laisser réduire (to reduce). Ça mijote works equally well on a stove and in someone’s head.