Heat canola oil in a 4-quart pot over medium heat.

Add ginger, garlic, cumin, black peppercorns, asafoetida, and salt.

Cook, stirring constantly, for 1 minute.

Add tomatoes and cilantro and cook for 5 minutes, stirring occasionally.

Add 2 cups of water and cook for 8 minutes on low heat.

Add the mussels, cover, and cook for 5 to 6 minutes, or until the mussels are opened.

Remove from the heat.

Transfer the mussels and broth to a serving bowl.

Prepare tempered oil by heating oil in a small pan over medium heat.

Add curry leaves and mustard seeds; when the mustard seeds begin to pop, remove the oil from the flame (about 30 seconds).

Drizzle the tempered oil over the mussels and broth and serve immediately.