Wash the chicken thighs under cold water and pat dry. Slice onions thinly and mince garlic cloves. In a bowl, combine chicken, garlic, onions, lemon juice, mustard, and spices. Coat chicken evenly and marinate for at least 2 hours, or overnight.

Remove chicken from marinade, scraping off any excess marinade. Reserve the marinade for later.

In a skillet, heat olive oil and add chicken thighs. Brown each side for 4-5 minutes until golden and crispy.

Remove chicken and set aside. Reduce heat, add onions to skillet, and sauté for about 5 minutes until soft and golden.

Pour reserved marinade into skillet, add browned chicken, and then add chicken broth. Cover and let simmer for 15-20 minutes until fully cooked.

Adjust salt to taste before serving. Serve over cauliflower rice or steamed vegetables.