Soak the deseeded anchos in water for about 30 minutes.
Toast the fenugreek seeds, coriander seeds and peppercorns in a dry skillet set over medium heat, about 2 minutes or until the spices start to get fragrant and the coriander seeds turn a couple of shades darker. Don't walk away because you do not want the fenugreek-- or anything else-- to burn.
Remove the spices from the skillet and set aside to cool.
Toast the soaked anchos and the arbol chilies in the skillet until they start to change color. Flip over and toast the other side. Altogether this won't take more than 2 minutes.
Add the anchos, arbol, toasted spices, onion, garlic and cashew nuts to a blender. Add enough water to make a thick, smooth paste. I like to make mine really smooth because I love the velvety texture of the finished curry.
Heat the oil in a saucepan.
Add the mustard seeds and when they sputter, add the curry leaves.
Toast for a few seconds, and then add the blended chili and onion paste.
Cook over medium heat, stiirring constantly, until the mixture turns a few shades darker and the water has evaporated.
Add the tamarind pulp along with 1 cup water. If the curry is too thick, add more water.
Add salt, bring to a boil, then reduce the heat so the sauce simmers. Let it cook for 15 minutes without covering it.
Add the tofu cubes and let the sauce simmer for another five minutes.
Add the coconut milk and jaggery. Mix well and warm through. Turn off the heat and garnish with coriander leaves.
Serve hot with Dill Rice (recipe below).