Heat 1 tbsp of oil in skillet on high heat then add fennel, mustard seeds and chillies.
Saute until mustard seeds begin to pop, then immediately add onions, garlic and ginger.
Saute to combine flavors for a few minutes then add crushed tomatoes, and mix to combine some more.
Lower heat to medium and allow tomatoes to heat throug
Add, cumin, salt, pepper and bay leaves and mix thoroughly.
Cover lower heat to low and allow to simmer for 1 hour.
Remove bay leaves from sauce, then remove from heat and transfer to heat proof container and allow to cool for 15 minutes.
Wipe skillet clean and then quickly rinse with hot water. Dry off with paper towels and set aside.
Once sauce has cooled a little, transfer to blender and blend on a high setting until ingredients have pureed.
Once sauce appears smoother, decrease blender speed to low and add yogurt.
Once yogurt is combined, add vegetable stock.
Blend until ingredients are combined and set aside.
Heat remainder of oil in skillet on high heat, then add onions.
Saute onions until flavor releases.
Add lamb and saute further for two minutes.
Pour sauce over lamb and carefully combine.
Return bayleaf to sauce, cover skillet and lower heat to simmer.
Allow to cook for 1 hour.
Serve with white rice.