Ingredients

• 4 limes
• 7 navel oranges, divided
• 2 small jalapeños, divided
• 1 cup sugar
• ½ tsp. kosher salt
• Club soda (for serving)

Instructions

1. Juice limes and 6 oranges into a large pitcher. (You should have about ¾ cup lime juice and 1¼ cups orange juice.) Discard lime rinds and half of the orange rinds. Cut remaining orange rinds into quarters and place in a large saucepan.
2. Coarsely chop 1 jalapeño and add to orange rinds along with sugar and salt. Using a muddler or dowel-style rolling pin, muddle rinds until thoroughly smooshed and much of the sugar and salt is dissolved, about 3 minutes. Stir in 1 cup warm water and let sit at least 10 minutes and up to 1 hour.
3. Strain orange mixture through a fine-mesh sieve into pitcher with juice, gently pressing with a spoon to extract as much liquid as possible; discard solids. Thinly slice remaining orange and add to pitcher. Remove seeds from remaining jalapeño; thinly slice into rounds and add to pitcher.
4. To serve, pour 2 oz. juice mixture into an ice-filled glass. Top off with club soda; stir to combine.
5. Do Ahead: Juice mixture can be made 2 days ahead. Cover and chill.