Bring a medium pot to med-high heat. Add a splash of water and your diced onion. Allow the onion to sauté for 4 minutes, adding more water as needed to prevent sticking.
Add your garlic to the pot and continue to sauté for 1-2 more minutes
Add your tomato paste to the pot and mix so that the onions and garlic are evenly coated.
Add your canned tomatoes (with juice) and vegetable broth to the pot. Bring it to a simmer, lower the temp to medium, and allow to cook for 30 minutes.
Drain your soaked cashews. Add the contents of your pot, your soaked cashews, and maple syrup to a high powered blender. Blend until smooth.
Add your basil, salt, and pepper to the blender. Blend until the basil has broken up into very small pieces that are evenly dispersed throughout the soup (or until completely smooth if desired).
Serve, top as desired, and enjoy!