Heat a skillet over medium-high heat. Add lamb, ½ teaspoon salt and ¼ teaspoon pepper. Cook, breaking the meat apart with a spoon, until brown all over. Drain excess fat, if needed.

Add onion and achaar and continue to cook until onions start to soften. Add chicken stock and bring to a boil, then lower to a simmer, stirring occasionally, until most of the liquid has cooked out.

While the lamb is cooking, using a mortar and pestle, grind together the garlic and ½ teaspoon of salt until it turns into a thick paste. If you don't have a mortar and pestle, you can smash the garlic and salt together on a cutting board with the side of your knife several times, until it forms a paste. Combine the garlic paste, yogurt, lemon juice and mint in a bowl (or in your mortar, if it's large enough). Set aside.

Bring a large pot of salted water to a boil. Cook gnocchi according to package directions.

To serve, divide gnocchi between bowls. Top with spiced lamb mixture and a few spoons of yogurt sauce. Sprinkle a little sumac over the top of everything, and garnish with cucumber, lemon and mint, if desired.