Add kumquats, sweetener, and 1/2 ounce gin (amount as original recipe is written // adjust if altering batch size) to a serving glass and muddle to break down sweetener and release citrus juices. Add remaining gin and stir well to combine.
If you’re not into citrus pulp/skin, scoop out or strain the kumquats from the drink. The whole fruit is edible though, so I left mine in! Otherwise, move onto the next step.
Add ice and top off with sparkling water to achieve desired strength of drink. Add 2-3 ounces for a stronger drink and 3-5 ounces for a weaker drink (amounts as original recipe is written // adjust if altering batch size).
Taste and adjust sweetness and strength as needed. Optional: Garnish with additional kumquat slices. Serve.
*If subbing lime for kumquats, add 1/2 lime, juiced, to the cocktail when sweetening. Then slice the other half for garnish. *Nutrition information is a rough estimate for 1 Gin and Tonic with 1 Tbsp sweetener.