Remove one roasted red pepper from a jar and blot any excess moisture. If roasting the pepper yourself, cut the pepper in half and remove the inside seeds and membrane. Place the cut side down on a baking sheet and lightly coat with oil. Roast the pepper at 450 degrees for 20-25 minutes. Let cool and gently peel off the skin.
Add the roasted red pepper, mayonnaise, and salt to a blender or food processor. Blend until creamy and well combined.