Add water and cashews to a blender, and process until smooth.
In a large pot, heat olive oil on medium-low heat. Sauté onion and garlic for about 2 minutes. Add blended cashew mixture, canned tomato, vegetable broth, dried herbs, and sugar.
Bring to a boil on medium-high heat, then reduce to the lowest setting and let simmer for 10 minutes.
Add salt to taste (I used one tablespoon for reference). Blend in batches until smooth, then serve while hot.
You can also let this cool at room temperature, then keep in your fridge for up to 5 days, reheating small amounts as necessary.