Heat 2tsp oil in a saute pan. Add the tempering ingredients and once the seeds start to splutter, add the cabbage, potatoes (if using), green peas and salt.
Cover and cook on medium heat until the veggies are tender, about 8-10 minutes.
In the meantime, grind all the ingredients listed under spice paste using very little water.
Add the spice paste to cabbage mixture and cook until the raw smell of onion is cooked, about 5-6 minutes.