Discard the tough stems from the greens. Chop the tender stems and set aside, then roughly chop the leaves.
Heat the oil in a 4-quart pot over moderately high heat until it shimmers and add the asafetida and cumin seeds. Cook, stirring until the spices are fragrant, about 1 1/2 minutes. Add the shallots, ginger, and chile and cook, stirring, until the shallots are translucent, about 3 to 4 minutes. Add the stems of the greens and salt to taste, then cook, stirring, for 1 minute. Add the greens and cook, tossing occasionally with tongs, until just tender, 15 to 20 minutes. Discard the chile and season with salt and pepper to taste.
If you want a spicier dish, break the chile into smaller pieces.
Adapted from One Spice, Two Spice