Whisk together the ketchup, lime juice, soy sauce, shallot, radish, ginger, chile, sugar and cilantro in a medium bowl and season lightly with salt and pepper. Cover and refrigerate for at least 30 minutes before serving. Can be made 8 hours in advance and refrigerated, do not add the cilantro until ready to serve.
Heat the grill to high.
Toss the shrimp with the oil and season with salt and pepper. Place onto skewers and grill for 1 to 2 minutes per side until lightly golden brown and just cooked through. Serve sauce in a bowl, surrounded by the shrimp.