Heat mustard oil and fry the onions till they are golden brown. Strain the oil and keep aside to use in marination later. Grind the onions finely.
Heat another clean pan. Add green cardamom, bay leaves, poppy seeds, coriander seeds, white cumin, black cumin and red button chilies. Roast these for 1-2 mins on medium-high heat until they are fragrant.
Cool slightly and add to your grinder. Grind till they turn into a powder.
In this powder, further add mace powder, nutmeg powder, salt, red chili powder, paprika powder and garam masala. Mix. This is your Bihari Kabab seasoning.
To the beef strips, add the prepared seasoning, yogurt, ginger garlic paste, meat tenderizer and the leftover mustard oil. Mix well and leave to marinate for 2-4 hours. If you plan to marinate overnight then add the meat tenderizer just 2 hours before cooking.
Take a metal or wooden skewers. If wooden, pre-soak them in water for 30 mins to avoid burning. Take a strip of beef and start threading it into your skewer. Thread 4-5 beef strips onto each skewer (it may vary depending on the length of your skewer). See the process in the video above.
At this point, you can barbecue these kababs on a charcoal grill or bake them in oven.
For pan-frying, heat 1-2 tablespoon of mustard oil in a pan. Then place your skewers and cook till they are no longer pink and cooked through.
Put all the Bihari Kabab in a deep pan with a lid. Place a piece of foil in the middle and put a hot coal on it. Drizzle some oil and immediately cover the pan with lid or foil tightly. Give smoke for 8-10 mins.
Garnish with fresh coriander, lemon wedges and red onion slices.
Video
Notes
Use 4-6 unsalted cashews if poppy seeds are not available.
In Pakistan, you can ask your butcher to give you 'pasanday' meat or undercut meat for Bihari Kabab.
If you have whole nutmeg and mace, then add it to the grinder with the roasted spices.