Heat oil in a wok or large deep skillet over medium heat. Add kalonji seeds and when they begin to sizzle add cumin seeds and allow both to sizzle for 45 seconds. (Don't let the cumin burn.).
Reduce heat and add onions. Saute for 10 minutes or until golden. Add garlic. Cook until garlic is golden, then add ginger, tomatoes and tomato paste. Stir well. Add salt, turmeric, cayenne and garam masala. Cook until oil separates from sauce, about 5 minutes.
Add chicken pieces and cook, uncovered, on medium heat for about 10 minutes, stirring occasionally. If the chicken or the sauce is burning, add 1/2 cup/125mL water. Cover and cook for 20 minutes or until chicken is thoroughly cooked. Stir in cilantro.