In a heavy bottom pot, add oil, we Gujarati's usually use Groundnut oil, but you can even use any cooking oil of your choice.
To this add Mustard Seeds, and let it splutter. Then, add hing. Now hing is optional, you can totally skip it.
Next, add in turmeric, and one chopped-up boiled potato. I use a boiled potato o make the cooking process faster. All I do is cut the potato into two halves, add it to a microwave-safe bowl along with water, use the boil option on my microwave, and it gets ready in 10 mins. On the contrary, if you want to cook the potatoes while making the shaak, at this point add about 4 Tbsp's water, cover, and let the potatoes cook until fork-tender.
Now add the chopped cabbage, Peas, and Tomatoes. Along with this, add salt, a tiny bit of sugar, red chili powder, turmeric, and coriander powder. Give everything a good mix. let it cook.
Once the peas are cooked, and cabbage is softened, there you have it! You Cabbage and Peas nu Shaak is ready.