On stovetop, heat a splash of olive oil at medium-high in an ovenproof pan with high sides. Sear chicken thighs on both sides until golden brown. Remove chicken to a plate.
Add chopped onion and chili flakes to the pan. Sauté until onions are brown and crispy. Mix in tomato paste and chicken stock. Stir in barley, then return chicken thighs to pan and sprinkle with fresh thyme.