They're usually made with berries such as blackberries, elderberries, blueberries and the like. The speaker provided a recipe for one made with habanero peppers!
Marion's Habanero Shrub
1/4 cup ripe blemish-free habanero peppers
1 cup apple cider vinegar
About 1 cup honey
2 tbsp cocoa (or to taste)
1/2 vanilla bean
If you're not that adventurous, try this Blackberry Shrub!