In a large bowl, combine all the ingredients for the grenadine sauce. Add the shrimp to the bowl and toss to make sure each shrimp is coated.
Heat some olive oil in a cast iron pan over medium high heat. Add the shrimp to the pan, reserving the extra sauce. Cook the shrimp for about 3 minutes on each side or until opaque and cooked through. Remove from pan and set aside. Pour the reserved sauce into the pan and bring to a boil. Lower the heat and cook the sauce for a few more minutes and it has thickened up.
Pour the sauce over the shrimp and top with the basil. Enjoy!