Mix together the turmeric, pepper and salt.
Rub the turmeric black pepper, and salt all over the chicken and let marinate in the refrigerator, covered, for 30 minutes.
In a small skillet over medium heat, dry-roast the mustard seeds for a few seconds, or until they are fragrant.
Remove from the skillet and repeat with the fenugreek seeds.
Be careful not to burn the spices.
Combine the mustard seeds and fenugreek seeds in a mortar and pestle or spice grinder and grind into a coarse powder.
Heat the oil in a wok or large saucepan over medium-high heat.
Add the garlic, ginger, ground spice mixture, cumin, chilies, and bay leaves and stir to combine.
Add the onion and saute until slightly translucent.
Drop in the marinated chicken and stir-fry for 4 minutes, then add the stock and tomatoes. Bring to a boil, then decrease the heat and simmer gently for 30 minutes.
Sprinkle with the chopped cilantro.
Serve with cooked white rice.