For the cilantro-lime dressing: In a cruet, shake together the lime juice, cilantro, grapeseed oil, sour cream and some salt and pepper until creamy. Set aside until ready to serve the salad.
For the arugula-corn salad: Bring a large pot of water to a boil. Add the corn and cook until crisp-tender, about 5 minutes. Rinse under cold water to cool. Cut the kernels from the cobs.
Combine the arugula, bell peppers, grape tomatoes and corn kernels in a large bowl. Add the dressing and toss to coat.