In a large bowl, soak raw cashews in hot water for at least an hour.
Meanwhile, prep remaining ingredients. Rinse and rough chop the sun-dried tomatoes. Peel and smash garlic. If using, rough chop the Thai red chili. Juice and zest half of a lemon.
Once the cashews have soaked for at least an hour and are tender to the touch, add them to a food processor or blender with 2 tablespoons of hot water and blend over medium-speed until a paste-like texture forms.
Add sun-dried tomatoes, garlic and Thai red chili (if using). Continue blending over medium-speed until well-combined.
Add basil, nutritional yeast, lemon juice/zest and tomato paste. Continue blending over medium-speed while slowly drizzling in extra virgin olive oil.
If pesto is too thick, while blending slowly drizzle luke warm water a ¼ cup at a time until desired texture is reached.