Place 3 cloves minced garlic, 1 inch minced ginger, 1 small green chili (sliced), 2 1/2 tablespoons white vinegar, and 3 large tomatoes (quartered) in a blender. Blend until smooth.

Pour the blended mixture into a large bowl. Add 2 pounds diced lamb leg and 1/4 cup vindaloo paste (or curry paste). Mix thoroughly so all lamb pieces are well coated. If you have time, cover and refrigerate to marinate for 30 minutes.

Heat 2 tablespoons ghee (or butter) in a Dutch oven or deep pot over medium heat. When the ghee is hot, add 2 small chopped onions and cook, stirring occasionally, until softened and translucent, about 5–7 minutes.

Add the coated lamb and the blended marinade to the pot with the onions. Stir to combine and increase the heat to bring the mixture to a gentle boil.

Add 3 small chopped potatoes to the pot. Reduce the heat to maintain a gentle simmer, leave the pot uncovered, and cook for 40–45 minutes, stirring occasionally, until the potatoes are tender and the lamb is cooked through.

Remove from heat and taste; adjust seasoning if desired before serving.