Step 1

Place kumquats and enough water to cover by 1/2 inch in a small saucepan. Bring to a boil over medium-high. Remove from heat; drain. Repeat blanching process; drain well. Process drained kumquats and 1/3 cup cold water in a blender until smooth, about 30 seconds. Using the back of a spoon, press mixture through a fine wire-mesh strainer into a bowl; discard solids. Set puree aside.

Step 2

Combine Riesling, 3/4 cup sugar, corn syrup, salt, and 1/4 teaspoon citric acid in a small saucepan. Cook over medium, swirling pan occasionally, until a candy thermometer registers 260°F (hard-ball stage), 15 to 25 minutes. Stir in kumquat puree (temperature will drop). Cook, stirring constantly, until thermometer registers 240°F, 5 to 10 minutes. Remove from heat, and let cool, stirring occasionally, until temperature reaches 200°F, about 5 minutes.

Step 3

Meanwhile, stir together gelatin and remaining 1/3 cup cold water in a small bowl. Set aside to bloom, about 5 minutes.

Step 4

Remove candy thermometer, and gently stir gelatin mixture into warm syrup until gelatin is dissolved and mixture is smooth. Let stand at room temperature 5 minutes. Skim off any foam that forms on surface. Place a 140-cavity half-sphere or semi-sphere (about 3/4-inch cavity) silicone candy mold on a large rimmed baking sheet. Carefully spoon 1/4 to 1/2 teaspoon mixture into each cavity. Alternatively, pour mixture into a 9- x 5-inch loaf pan. Chill mold on baking sheet, uncovered, until candies are set, at least 4 hours or up to overnight.

Step 5

Remove gummies from mold, and place on a wire rack. (If using a 9- x 5-inch loaf pan, use a sharp knife to cut gummies into uniform squares.) Let stand at room temperature in a cool, dark place, uncovered, until gummies are no longer sticky and have dehydrated to desired degree of chewiness, 1 to 3 days. If gummies reach desired chewiness but are still slightly sticky, toss batches of 6 gummies with a few drops of grapeseed oil to coat. Store in an airtight container up to 2 weeks.

Step 6

Just before serving, stir together remaining 1/4 cup sugar and remaining 3/4 teaspoon citric acid in a small bowl. Dip bottom of each gummy in sugar mixture. Sugared gummies can be held at room temperature up to 4 hours.