In a saucepan / kadai, heat oil. Once the oil is hot, add mustard seeds and let them splutter.
Add cumin seeds and let them sizzle.
Add finely chopped onion, saute for 2-3 minutes.
Add roughly crushed ginger-garlic and saute till the raw smell of ginger-garlic fades away.
Add finely chopped tomatoes.
Cover and cook this mixture till tomatoes are tender.
Once tomatoes are soften add red chilli powder, turmeric powder, coriander powder, cumin powder and garam masala powder. Saute this masala for a minute on low flame.
Add 1/4th cup water to prevent spices from burning.
Cook this masala for a minute or two till oil seperates from the edges.
Add fresh green peas and cubed potatoes, mix well with the onion-tomato masala.
Add very little salt for peas and potatoes at this time. (Incase, using frozen peas, add it along with the cauliflower later)
Add half a cup of water and let potatoes & peas cook for 7-8 minutes on medium flame or till half done.
Using a knief or spoon check if potatoes and peas are half cooked.
Now add cauliflower florets and mix. At this point, add salt to taste and half a teaspoon of sugar.
Add half cup of water for the vegetables to cook.
Cover and cook aloo gobi matar till vegetables soften.
Once vegetables are tender, add amchur powder (raw mango powder) and finely chopped coriander leaves.
Aloo Gobi Matar Sabzi is ready.
Serve with any flatbread of your choice or with rice.