Step 1

In a small skillet over medium-high heat, toast the cumin, coriander and peppercorns until fragrant, about 1 minute. Transfer to a spice grinder or mortar and grind. Add tumeric, paprika, and cinnamon, set aside.

Step 2

In a large, deep skillet or dutch oven heat the oil over medium-high heat. Add the mustard seeds, shallots and serrano pepper with a pinch of salt and pepper and sautee until the shallots begin to brown, about 5 minutes.

Step 3

Add tomato paste, garlic, ginger and spice mixture and cook until fragrant, 2-3 minutes.

Step 4

Add potatoes, water, vinegar, brown sugar and a pinch of salt. Bring to a boil, reduce heat and let simmer, covered, for 25-30 minutes, until the potatoes can be pierced with a fork easily.

Step 5

Remove lid and cook for an additional 5-10 minutes until the sauce has thickened.

Step 6

Serve with greek yogurt, cilantro and mint if desired.