Step 1.
- Fill an Old Fashioned glass with ice.
Step 2.
- Pour in 1.5 oz Campari.
Step 3.
- Add 1.5 oz sweet vermouth.
Step 4.
- Top with soda water (about 2 oz, adjust to taste).
Step 5.
- Stir gently to combine.
Step 6.
- Garnish with an orange slice.