Heat oil and butter in a wok over medium-high heat.
Add chicken pieces and fry until golden brown. Remove chicken and set aside.
In the same oil, add garlic and ginger paste. Stir fry for 3 minutes.
Add diced tomatoes and fry until softened.
Add all spices (salt, cumin seeds, dried coriander, black pepper, red pepper flakes, garam masala) and fry briefly.
Return fried chicken to the wok, add yogurt, and fry for 8-10 minutes.
Cover with lid and cook until oil rises to the surface.
Add dried fenugreek, chopped fresh coriander, green chilies, and lemon slices.
Cover and cook on low flame for 5 minutes.
Serve hot with homemade chapati or roghni tandoori naan.