Heat oil in a medium sized pot over low to medium heat. Add the cumin seeds and cook until they start popping (about 30 seconds). You don’t want to burn them!
Add the onions and ginger then sauté until golden brown (about 6 - 8 minutes).
Add ground coriander, ground cumin, garam masala, turmeric, and cayenne pepper, if using. Heat through until fragrant (about a minute).
Add the tomatoes and tomato paste. Add in 1/2 cup of water and simmer for 5 to 10 minutes. Remove from heat and allow mixture to cool slightly.
Add the cashews into a blender along with the tomato mixture. Blend for one minute or until creamy.
Place this sauce back in the pan and decide if you’d like to add in more water to get the consistency you’d like. Simmer over low-medium heat to heat through for about one to two minutes.
Serve over or alongside cooked chicken, chickpeas, tofu, or paneer!
Top with chopped cilantro, if desired.