Pound the garlic and ginger along with cumin seeds using mortar pestle. Keep ready.
In a wide kadhai or heavy pan, add the oil and warm on low medium heat until its slightly smoky.
Carefully add the poatoes to the oil, sprinkle a pinch of salt. Brown the poatoes on all the sides. Do not cook them through. Once browned, take out in a bowl and keep near.
Remove the kadhai from stove and temper the remainng oil with bay leaf, cardamom and cloves. Add hing. Saute for 10 seconds, be careful the spices might crackle.
Return the kadhai/pan back to stove. Next, add the ginger-garlic that we pounded earlier and saute in hot oil for 10 seconds. Dont let burn.
Add the chopped onions next and on low medium heat brown the onions stirring regularly to a nice golden color.
Once the onions are browned, add all the powdered spices- corinader, chilli power, tumeric to the pan. Add 2-3 tablespoon of water. Saute the spices very well for 3-5minutes in oil. Once you see oil bubbles seperating, add the tomatoes and pinch of sugar. Saute the tomatoes with onions and spices for 5-6 minutes on low medum heat till you see that the masala is deep in color and the oil is seperating again.
Add the ground peas along with julinned ginger(if using) and mix well with the masala.Also add the reserved peas. Saute the peas with the masala for good 6-7 minutes, scrapping the sides and bottom of pan since the peas have a tendency to stick.
The peas will slowly start turning brown. Keep on sauteing till you see that the peas are lightish brown and bit shiny.
Add about a cup and a half of warm water. Add the potatoes as well. Mix everything, it should be a thick curry right now. Taste and adjust the salt. Bring to a slight boil, cover with a lid, reduce the stove to low and let simmer for 12-14 minutes untill the potatoes are fork tender. If you feel that thenimona is getting too thick for your liking, add ¼ cup or more water. Simmer after you add water. Dont make very watery though. You will see a little thin layer of oil on stove by the end. Nimona is ready
Mix in the amchoor and roasted cumin powder. Add the tempering(if using). Mix well. Cover and let rest for atleast 30 minutes before serving.