Make the curry: In a large, heavy-bottomed pot or Dutch oven, heat the oil over medium heat. Add the mustard seeds and cook until they begin to pop and sputter, 1 to 2 minutes.
Add the fried garlic and ginger and stir until fragrant, about 30 seconds. Add the onions, pandan or curry leaves, and tomatoes, and cook until the onion is slightly softened, 3 to 4 minutes.
