In a bowl, mix together lemon juice, minced garlic, Dijon mustard, vegetable oil, black pepper, paprika, cumin, coriander, and salt.
Rub the mixture over the chicken pieces and let marinate in the refrigerator for at least 1 hour, preferably overnight.
Heat the vegetable oil in a large skillet or Dutch oven over medium heat.
Remove the chicken from the marinade and brown the pieces on all sides until golden, about 5-7 minutes per side.
Remove the chicken from the skillet and set aside.
In the same skillet, add the sliced onions and cook until they are caramelized and golden brown, about 15-20 minutes. Stir frequently to prevent burning.
Add the chopped tomatoes to the onions and cook for another 5 minutes.
Stir in the chicken broth, white vinegar, ground turmeric, paprika, black pepper, and salt.
Return the chicken pieces to the skillet, making sure they are covered by the sauce.
Cover and simmer on low heat for 30-40 minutes, or until the chicken is cooked through and tender.
Garnish with fresh parsley or cilantro and lemon wedges if desired.
Enjoy your meal!