Throughly wash the head of the cabbage, potatoes, and bell pepper under running water. Quarter the head of the cabbage and remove the hard core.
Thinly slice quartered cabbage like coleslaw and julliene potato and pepper. If needed, pat dry the julliened potato and pepper with a paper towel to dry excess moisture. Set the vegetables aside.
Heat oil in a large skillet or wok on high heat. Add mustard seeds, cumin seeds, and whole chilies to hot oil.
Once mustard seeds start to pop, add julliened potatoes. Stir to coat the potatoes in oil tempering. Let potatoes cook over high heat for 2 minutes without stirring.
Stir potatoes and continue to cook for an additional 2 to 3 minutes or until fully cooked. Add julienned green bell pepper. Stir and continue cooking on high heat for about 1 minute.
Now quickly add all the thinly sliced cabbage, ground spices and salt to the wok.
Stir well to coat and season the cabbage evenly. Continue to cook on high heat while stirring continuously for about 2 minutes.
Turn the heat off and set the stir-fried cabbage aside. Garnish with chopped cilantro.
Serve it warm as is or as a side dish to Dal and Chawal.