1 tbsp. whole black peppercorns
1 tbsp. black mustard seeds
2 tsp. cumin seeds
2 tsp. coriander seeds
1 tsp. fenugreek seeds
5 whole cloves
1 1" stick cinnamon
¼ cup Hungarian paprika
¼ cup palm vinegar
1 tsp. ground turmeric
1 tsp. light brown sugar
16 cloves garlic, minced
1 2" piece ginger, peeled and minced
2 lb. boneless, skinless chicken thighs, cut in half
3 tbsp. canola oil
2 large yellow onions, finely chopped
10 thin green Indian chiles, stemmed, seeded, and minced
1 lb. small new potatoes, cut in half (cut in quarters if large)
Cooked white rice, for serving