In a large bowl, whisk together the Greek yogurt, lemon juice, ginger-garlic paste, 1 teaspoon garam masala, turmeric, chili powder, and salt.
Fold the fish cubes into the marinade gently and refrigerate for 20 minutes.
Preheat the oven broiler to high and line a baking sheet with parchment paper or a wire rack.
Place the marinated fish cubes on the tray and broil for 5 to 7 minutes until the edges are slightly charred and the fish is opaque.
While the fish is broiling, heat ghee in a large pan over medium heat. Add cumin and the remaining 1 teaspoon of garam masala.
Pour in the tomato puree and simmer for 5 minutes until the sauce thickens and oil begins to separate.
Stir in the heavy cream and dried fenugreek leaves, simmering for an additional 2 minutes.
Gently transfer the broiled fish cubes into the sauce, folding carefully to avoid breaking the pieces.
Garnish with fresh cilantro and serve immediately.