The longer the spices infuse in the rum, the more flavourful this dark and stormy will be.
A spice mill or mortar and pestle
Coarsely grind allspice and peppercorns in spice mill or with mortar and pestle; add spices and orange zest to rum and let infuse at least 2 days. Strain into a clean bottle or a glass jar.
DO AHEAD: Rum can be infused 3 weeks ahead. Store in a dark, dry place.
Combine lime juice and 4 oz. spiced rum in a cocktail shaker; fill with ice. Shake until outside is frosty, about 30 seconds. Strain into highball glasses filled with ice, top off with ginger beer, and garnish with lime wedges.
2 teaspoons allspice berries
2 teaspoons black peppercorns
4 1” strips orange zest (removed with a vegetable peeler)
1 750-ml bottle dark rum
3 oz. fresh lime juice
1 12-oz. can ginger beer
2 lime wedges (for serving)