Prepare and measure ingredients. Place them on counter near stove.
Pour olive oil into large heavy bottom skillet. Make sure skillet's lid is close by. Use wooden spoon to stir olive oil around skillet. Turn heat on low.
Quickly add mustard seeds, ground cumin, mild chili powder, ground ginger, smoked paprika (if using), cayenne pepper (if using). Stir together until evenly combined (about one minute). When mustard seeds start popping up, cover pan with lid. Make sure heat is still on low.
Remove lid. Add thyme seeds, chopped tomatoes, chopped onions and 1/4 cup of water. Season with preferred amounts of salt and coarse ground black pepper.
Stir until well combined.
Simmer (without lid) to desired thickness.
Remove from heat. Taste a cooled sample.
If desired, add more of each seasoning until satisfied with taste. Simmer over low heat and stir constantly for 2 minutes.
If desired, pour into blender and blend until desired smoothness.
Serve hot (chunky or smooth).
Store in a container with a tight lid. Keep refrigerated.