Heat your choice of cooking oil in the skillet over medium heat.
Add mustard seeds. Let the mustard seeds splutter a little (hold a lid or a plate to cover the skillet to avoid seeds flying out). The spluttering releases the aromatic mustard flavor in the oil. At this time, add turmeric powder and cumin seeds.
Add the garlic. Saute the garlic for a couple of minutes, until the garlic is fragrant.
Stir in medium sized cubed tomatoes and add salt
Let the tomatoes cook for a bit. Add sugar, tamarind paste and cayenne or red chili powder according to taste and stir well.
Let it simmer for a minute or two. Serve with rice or naan!