Heat coconut oil in a medium Dutch oven over medium until shimmering, about 1 minute. Add mustard seeds, and cook, undisturbed, until seeds begin to pop and crackle (stand back so they don’t pop in your face), about 1 minute. Add onion, jalapeños, garlic, and ginger; cook, stirring occasionally, until onion is softened, 5 to 7 minutes.
Stir tomato into onion mixture in Dutch oven. Stir in curry leaves, coriander, salt, garam masala, asafoetida, and turmeric. Cook, stirring often, until mixture browns slightly, 3 to 5 minutes.
Add cauliflower, potato, and frozen vegetables to Dutch oven, stirring to completely coat in spice mixture. Cover Dutch oven; reduce heat to low, and cook, stirring occasionally, until potato and cauliflower are just softened, 20 to 30 minutes. (Add about 2 tablespoons water, if needed, if bottom of Dutch oven is looking very dry.)
Stir chickpeas and coconut milk into Dutch oven; increase heat to medium, and bring to a simmer. Simmer until heated through, about 3 minutes. Season with additional salt to taste. Serve over steamed rice or alongside warm parathas.
