Cut the tomatoes and shell the green peas.In a kadai pour oil and when it gets heated add mustard,channa daland slit green chilies.Add tomatoes and green peas.When it is cooking add turmeric powder,sambhar powder and mix well.Cook moong dal in a pressure cooker and set aside.Add cooked dal and salt to the tomato and peas mixture.Cook for 2 minutes and add half a squeeze of lemon.Garnish with coriander leaves.Serve hot with chappathis or phulkas.