In a large bowl, whisk together 6 tablespoons olive oil, the lime peel, lime juice and oregano. Add the black beans, escarole, jicama, scallions and cilantro; toss. Season with salt and pepper; divide among 4 plates.
In a large skillet, heat the remaining 2 tablespoons olive oil over high heat. Add the shrimp, season with salt and pepper and cook, turning once, until just opaque, about 5 minutes. Arrange on top of the bean salad and sprinkle with more cilantro.