with the traditional basil-based pesto, all would probably work very well as pasta sauces. Other traditional pesto applications are equally good - as a dip for vegetables or breadsticks, a garnish, a condiment, a spread for bread or on a savory sandwich instead of mayonnaise, or swirled into a light sauce to boost the flavor.
How do I determine how much orange oil to use in place of grated orange peel? What would the ratio be?