Heat oil in a pot. Add chopped onions, garlic, ginger and cumin seeds and saute till the onions become golden brown
Add in the tomatoes, spices and 3/4 cup of water. Cook on high till the tomatoes break down and a the gravy thickens slightly, about 4-5 minutes
Add the chopped carrots, potatoes. Turn the heat down to the lowest setting and cover, allowing the vegetables to steam-cook. They will take 15-20 minutes to cook, depending on how thick they were sliced.
5 minutes before the vegetables are cooked through, add the dried fenugreek leaves. If there is too much water left by the time the vegetables are cooked, uncover and cook on medium till the water evaporates.
Avoid stirring the curry when the potatoes are cooked as this may break them.