4 large navel oranges, plus wedges for serving
2 large lemons, plus wedges for serving
3Tbsp. pure maple syrup
1/2 tsp. (or more) cayenne pepper
1tsp. Diamond Crystal or ½ tsp. Morton kosher salt
Remove zest and white pith from 4 oranges and 2 lemons; discard. Slice citrus into 1”-thick rounds and remove seeds; discard. Arrange in a single layer on a parchment-lined baking sheet and freeze until firm, at least 2 hours and up to 12 hours.
Transfer frozen citrus to a blender and add maple syrup, cayenne, salt, 10 ice cubes, and about ½ cup water. Blend, adding more water 1 Tbsp. at a time if too thick to blend, until smooth. Taste and add more cayenne if desired.
Divide slushy among glasses and garnish with orange and lemon wedges. Makes 4