On a griddle, or in a cast iron skillet, melt butter over medium heat but do not brown.Spoon hoecake batter onto griddle, about ½ cup per cake, to make 4 hoecakes.As hoecakes cook, bubbles will appear and burst on surface of cakes. When cakes are well covered with burst bubbles, about 2–3 minutes, carefully turn cakes over with a spatula and cook for another 2–3 minutes. Remove from pan and keep warm.Meanwhile, bring pot likker broth to a boil in a medium saucepan. Add shrimp, ensuring that they are completely submerged, and remove pan from heat. Allow shrimp to poach for 3 minutes and remove from pot likker.Arrange 3 shrimp on top of each hoecake, top with marinated cucumbers and onions, and garnish with whiskey old sour crème fraîche.Hoecake BatterCombine cornmeal, salt, baking powder, and baking soda in a bowl.Combine melted butter, egg, and buttermilk in a separate bowl.Add liquid mixture to dry mixture and stir to combine.Pot Likker BrothCombine onion, garlic, red pepper, vinegar, and brown sugar in a medium pot over medium heat. Cook for 5–6 minutes, until cider and sugar are reduced to a syrupy glaze.Add chopped green stems and water, and season with salt and pepper. Bring to a simmer and cook for 30–45 minutes, until broth is slightly bitter from greens. Add more salt (this should be saltier than one would want to drink because it is going to be used to flavor the shrimp), strain, and set aside until needed.Whiskey Old Sour Crème FraîcheIn a plastic or glass container, combine heavy cream and buttermilk, stirring well.In a separate bowl, combine old sour, sugar, and rye whiskey, stirring well to dissolve sugar.Add old sour mixture to cream and buttermilk and stir well to incorporate. The mixture will begin to thicken at this point. Cover and leave in a warm spot for 24 hours. Refrigerate after 24 hours.Old SourCombine all ingredients in a clean, sterilized glass jar. Shake to combine.Cover jar with cheesecloth and store in a warm, dry place—away from light—for 5 days.After 5 days, strain and refrigerate.Marinated Cucumbers and OnionsIn a medium bowl, combine the sherry vinegar, sugar, honey, salt, and pepper.Add shaved cucumber and onion and marinate for 5 minutes.