Cut kernels from corn cobs to measure 2 3/4 cups; reserve 1/4 cup of the kernels in a small bowl for serving, and place remaining 2 1/2 cups kernels in a large bowl. Using large holes of a box grater, scrape liquid and remaining pulp from cobs into a small bowl. Discard cobs.

Melt butter in a medium saucepan over medium-high. Add bell peppers and onion; cook, stirring often, until tender, about 4 minutes. Stir in garlic, salt, black pepper, and the 2 1/2 cups corn kernels; cook, stirring occasionally, until corn is tender-crisp, about 4 minutes. Add corn liquid-pulp mixture and water; let come to a boil. Reduce heat to medium-low; simmer, undisturbed, until vegetables are tender, about 4 minutes.

Transfer corn mixture to a blender; add oil. Secure lid on blender, and remove center piece to allow steam to escape. Place a clean towel over opening. Process until smooth, about 2 minutes.

Pour corn mixture through a fine mesh strainer into a bowl, pressing with the back of a spoon to extract as much liquid as possible. Discard solids. Stir vinegar into strained corn mixture. Cover and chill at least 4 hours or up to 8 hours. 

To serve, ladle soup evenly into 4 bowls. Drizzle evenly with additional oil; sprinkle with reserved 1/4 cup corn kernels, and garnish with additional chopped bell pepper.