Start this recipe the night before by soaking the green chilli, cumin and coriander seeds in water in the fridge.
Preheat your oven to 160 degrees Celsius. Marinate beef ribs in garlic and ginger paste and set aside.
Place an oven proof dish over high heat along with the mustard oil and allow to warm up for 3-4 minutes. Add the Bengali spice mix to the hot oil and leave for 5 seconds, then immediately add the beef ribs and brown for 5-10 minutes.
Add the Bengali simmer sauce and cashews and stir to combine.Cover with a lid and place into oven for 3 1/2 hours or until meat is tender and falls off the bone.
Meanwhile in a mortar and pestle add the soaked cumin and coriander seeds along with the chilli and coriander leaves and grind to a fine paste.Once the ribs are cooked remove from the oven and allow to cool slightly before serving. Drizzle over the ground spice mix.