Whenever cold soups call for chicken broth, be sure to defat it completely for best results. Also, black pepper is the only spice in this chowder, so freshly ground is a MUST.
Place broth, corn cobs and dill sprigs in a heavy pot. Bring to a boil, reduce heat, simmer 10 minutes. Discard cobs and dill.
Add potatoes to broth and cook for 8 minutes or until tender. Add corn kernels and cook 1 minute longer. Remove from heat; pour soup through a strainer, reserving vegetables and broth.
Place yogurt and 2/3 of the diced cucumbers in the bowl of a food processor; pulse on and off just to combine ingredients (so some texture remains). With motor on, pour in 1 cup of reserved broth through feed tube and pulse machine on to just combine ingredients. Remove to a bowl. Save any leftover broth for another use.
Stir in the reserved vegetables, remaining diced cucumber, bell pepper and chopped dill. Season with fresh black pepper. Refrigerate for up to 2 hours. Serve chilled.
Per 1-cup serving: 212 calories, 2 grams fat, 5 milligrams cholesterol.
NOTE: If you like, cut 3 more ears of corn (with kernels) into 1" lengths and cook separately for 2-3 minutes. Then divide corn between bowls and ladle soup on top.