My mom usually make vellarikka (yellow cucumber) curry this way with slight difference. Cucumber is skinned, cut into cubes and then cooked with turmeric and red chilli powder. Ground paste of coconut, cumin seeds and shallots (pearl onions) and crushed mustard are added and finally seasoned with oil, mustard, whole red chilli and curry leaves. Note that butter milk or yogurt is not added to this curry. Serve with rice.
Recipe Courtesy: Simply Spicy