1. Place bell peppers directly over the flame of a gas-stove burner on high heat or on a grill. Roast peppers, turning with tongs, until blackened all over. (Alternatively, broil peppers on a baking sheet, turning, until skin has charred.) Transfer peppers to a large bowl, and cover immediately with plastic wrap. Set aside to steam, about 15 minutes. Peel peppers; discard skins. Remove stems, seeds, and ribs, and cut each pepper lengthwise into strips.

2. Place peppers in a small saucepan, along with wine, saffron, and garlic; simmer over medium-low heat until garlic has softened, about 10 minutes. Transfer to the bowl of a food processor; process until smooth. Slowly add olive and grapeseed oils; process until well combined. Add lemon juice and season with salt and pepper; pulse to combine.