How to Make It
In a medium saucepan, cover the pork with the water and Chicken Stock. Add the onion, carrot, celery, bay leaf, 1/2 teaspoon of salt and the peppercorns and bring to a simmer. Reduce the heat to low, cover and simmer, skimming occasionally, until the meat is very tender when pierced with a knife, about 2 1/4 hours. Transfer the meat to a plate and let cool completely, then coarsely shred with 2 forks. Strain the stock and refrigerate until chilled; discard the vegetables. Discard the fat from the stock and boil over high heat until reduced to 1 1/2 cups.
In a large saucepan, bring the pork stock and milk to a simmer. Whisk in the cornmeal, masa harina, lard, crushed red pepper and 1 teaspoon of salt. Stir over moderately low heat until thick and smooth, about 5 minutes. Remove from the heat and stir in the shredded pork and culentro and let cool. Shape the mixture into 8 ovals and wrap each in a rectangle of foil, twisting the ends securely.
In a medium saucepan, combine the orange, cherry and lime juices with the onion. Bring to a boil over moderate heat and cook until reduced to 3/4 cup, about 12 minutes. In a small skillet, cook the garlic in the olive oil over moderate heat until very lightly browned, about 3 minutes. Whisk the garlic oil into the reduced juices, add the dried cherries and season with salt and pepper. Let cool, then refrigerate until chilled, about 1 hour.
Spread the tamales in a single layer in a steamer. Cover and steam over several inches of boiling water until the cornmeal is no longer gritty, about 30 minutes. Add more boiling water to the steamer halfway through cooking.
In a bowl, toss the watercress, scallions and 1/2 cup of the cherry mojo and season with salt and pepper. Mound the salad on 4 plates. Unwrap the tamales and arrange 2 on each plate next to the salad. Spoon the remaining mojo onto the plates and serve.