Finely chop ripe tomatoes.
Heat sesame oil in a heavy pan, crackle mustard seeds, fenugreek seeds, and dry red chilies.
Add garlic paste and sauté for 1 minute.
Add chopped tomatoes and salt, cooking on low-medium heat, stirring frequently for 25 minutes until the tomatoes break down completely and release oil along the sides.
Cool and store in a jar, serving as a condiment with dosas or rotis.