Combine the sugar, white wine, and red wine in a large bowl and stir for several minutes until the sugar is dissolved. Stir in the sliced orange and lemon. Cover and refrigerate for 4 to 6 hours or overnight.
Stir the mixture and divide it into pitchers. Add the sliced fruit and serve the sangria over ice.
Adding sliced seasonal fruit is optional but highly recommended. To make a double batch of sangria, use 2 oranges, 2 lemons, 2 cups sugar, 6 1/3 cups (50 3/4 ounces) dry white wine, and 6 1/3 cups (50 3/4 ounces) dry red wine. Add fruit as desired. To make a 2-gallon batch for a large crowd (5 times the recipe), use 10 bottles of wine.
Per Serving: 278 calories;0.2 g fat;
36 g carbohydrates;
0.4 g protein;
0 mg cholesterol;
10 mg sodium.