What is a cocktail with very few ingredients but is still impressive and unusual enough to surprise people?

For an impressive cocktail with minimal ingredients that will surprise your guests, I recommend considering the The Perfect Martini as your top choice. With just three ingredients—gin, red vermouth, and olive juice—this cocktail manages to deliver a sophisticated and complex flavor profile. The botanical notes of gin are beautifully balanced with the herbal character of red vermouth, and the olive juice adds a savory twist. Additionally, its elegant presentation in a chilled cocktail glass with an olive garnish truly lives up to its name, making it a refined and eye-catching choice.

Another fantastic option is the Dry Martini 'Preferred'. Although similar in its simplicity, this version includes just three main ingredients—dry gin, white vermouth, and orange bitters. This cocktail offers a nuanced blend with a dash of orange bitters enhancing the classic dry gin and vermouth mix. It’s perfect for those who appreciate the intricacies of cocktail-making but don't want to go overboard with numerous ingredients. This drink is served in a cocktail glass with a minimalist elegance, making it a distinguished option that will impress any crowd.

Both of these selections excel in delivering a complex and sophisticated drinking experience while keeping the ingredient list impressively short. Their refined nature and elegant presentation make them stand out, ensuring your guests will be both surprised and delighted.