Simple easy to cook karahi

Ingredients Chicken ▢½ kg chicken, cut into pieces ▢⅓ cup oil ▢¼ teaspoon black pepper ▢½ teaspoon salt ▢1 small (100 gram) onion, very finely chopped Spices ▢½ tablespoon chopped garlic ▢½ tablespoon green chilli paste ▢1 teaspoon kashmiri red chilli powder, or paprika for red color ▢1 teaspoon coriander powder ▢1 teaspoon cumin powder ▢½ teaspoon dry fenugreek leaves, optional (kasuri meethi) ▢¼ teaspoon garam masala powder, optional ▢¼ teaspoon turmeric powder ▢½ teaspoon black pepper powder, freshly grounded ▢½ teaspoon red chilli, (skip red chilli if you like less spicy food) other ▢3 tomato , sliced or pureed ▢½ teaspoon salt Garnish ▢1 tablespoon butter, (optional) ▢1½ piece ginger, thickly grated ▢2 medium chillies ▢1 lemon, sliced in wedges