Bateka Nu Shaak

Name: Bateka Nu Shaak
Ingredients: 2 tbsp. vegetable oil or ghee; 0.5 tsp. brown mustard seeds; 0.5 tsp. cumin seeds; 1 medium onion, 1/4-inch dice; 2 garlic cloves, minced; 2 tsp. ginger paste; 2 Roma tomatoes, diced; 0.5 tsp. turmeric powder; 1.5 tsp. cumin powder; 1.5 tsp. coriander powder; 1 tsp. red chili powder (or to taste); 2 tsp. garam masala; 2 large Russet potatoes, 1-inch dice