Lightly toast the nuts in a dry pan over medium heat. Mix around in the pan until they are lightly toasted, careful not to burn.
Toss everything except the lemon in a high speed blender. Blend until almost smooth. Taste and add a light squeeze of lemon to your liking. Blend for another couple seconds. I like to keep it a little chunky. Blend smoother if you prefer.
Keyword appetizer, red pepper, romesco, sauce, walnuts