These ingredients find their way into reimagined favorites. A mai tai by Trash Tiki, for example, includes rum infused with discarded pistachio shells, and stock made of orange peels, boiled and blended almond croissants, lime husk citrus juice, and dried hibiscus. There’s some agave syrup in there too. Other drinks are more simple, such as a sweet and sour cocktail composed of strained apple pulp, sugar, water and citric acid.

Even the cardboard boxes are upcycled, into handmade coasters. As the couple says, single-use waste is just a lack of creativity.

“As soon as a waste item is created, you’re meant to create the second recipe,” said Ms. Ramage, 34. “Chefs have been doing it for centuries. It’s always been there. We’re just talking about it in a different way.”

The idea is to inject some fun into sustainability, which Mr. Griffiths said tends to be a dry and boring topic. He cited social media influencers posting photos of plastic-free groceries and “patting themselves on the back.”