Slice kernels off corn, if using fresh.
Heat vegetable oil in a wok or sauté pan over medium-high heat, add mustard seeds, and cover. When seeds stop popping, lower heat to medium and add chiles; stir 30 seconds.
Stir in turmeric. Add corn and salt to taste. Toss, turn heat to low, cover, and cook until corn is tender, about 5 minutes (cook frozen corn about 1 minute). Stir in cilantro. Serve warm.