Heat oil in a saucepan over medium heat. When hot, add cumin seeds and cook for 1 minute or until the cumin seeds get fragrant. Add chopped onions, garlic, carrot and a pinch of salt. Cook for 4 to 5 minutes or until onions are translucent, stirring occasionally. Add the coriander, turmeric, cayenne and pepper, and mix for a few seconds.
Add the onion mixture to a blender along with the tomatoes and water and blend until pureed.
Transfer the pureed tomato mixture back to the saucepan. Add bay leaf, salt and sugar and cook over medium heat for 12 to 14 minutes. Taste and adjust salt, sweet and heat. Adjust consistency by adding more water if needed. Garnish with green onions, vegan butter or non dairy cream and serve with crusty bread, croutons, or vegan grilled cheese sandwiches.
