In a medium saucepan, add the olive oil, flour, white wine vinegar, lemon zest, and chile powder. Stir until smooth (the lemon zest may have a little texture, but overall this creates a paste-like consistency).
Our sauce also works as a citrus-mayonnaise alternative (you’ll need add a little extra flour, approx. ½ teaspoon, to make it slightly thicker. Refrigerate the finished sauce. The refrigerated life on the gluten-free version of this sauce is short, a couple of days at most).