Heat vegetable oil in a skillet over medium heat. Stir in cinnamon, bay leaf, cardamom, and cloves to infuse the oil with the spices. Continue stirring for 2 minutes. Add onion, grated ginger and minced garlic and saute until onion is lightly browned.
Cube the chicken into 1 inch pieces and add ground spices (curry powder, paprika, cayenne pepper, sugar and salt) chicken, and tomato paste to the pan. Let the tomato paste burn just a little, then add yogurt and coconut milk. Bring to a boil, reduce heat, and simmer for 20 to 25 minutes.
Juice the lemon half into the pan and simmer 5 more minutes.