Marinades are typically comprised of fat, acid and seasoning. Yogurt contains all three. Lactic acid in yogurt breaks down the connective proteins and acidifies the muscle fiber which makes the meat juicier and more tender. At the surface level, yogurt makes a difference by acting as a buffer between the chicken breasts to direct heat and gives potentially tasteless fillets a flavor boost. (And, if you had time, you could pop these in the marinade to coat for up to 24 hours.)
Cooking with yogurt is a centuries-old technique, prevalent in Southeast Asian and Middle Eastern cuisines. In this recipe, we marry it with harissa, a hot chile paste used in Moroccan, Algerian and Tunisian cuisines. Harissa is more than just fire and heat. Chiles are blended into a thick paste with pungent garlic, rich olive oil, and bold, aromatic spices such as cumin, caraway and coriander. It’s a powerful combination of aromas and flavor. Substitutes could include Asian chile paste or even hot sauce, but harissa is readily available at grocery stores.