Ingredients :

• Chicken Breasts — Choose thick ones, not those thin cutlets that dry out in three minutes. Count on 150 g per person. If you have boneless thighs on hand, they work even better — the meat is more tender and handles simmering in the sauce without drying out.
• Plain Yogurt — Full-fat yogurt is preferred — 0% tends to release water when heated. Greek yogurt also works great; it gives an even thicker and more velvety sauce. Avoid flavored yogurts, for obvious reasons.
• Mustard — Classic Dijon mustard for a sharp, clean sauce. If you like texture, whole-grain mustard gives a more rustic and visually interesting result. Two generous tablespoons — don’t be shy.
• Onion — One medium yellow onion, finely sliced. The goal is to let it melt completely in the pan — translucent, soft, almost sweet — before adding anything else. It provides the aromatic base; don’t rush it.