To prepare the pork stew, season the pork with about 1 tablespoon kosher salt. In a Dutch oven or other large, heavy pot over medium-high heat, warm the olive oil. Working in batches if needed, add the pork and cook until browned on all sides. Transfer the pork to a plate. 

Add the onions and leeks to the pot and cook, stirring occasionally, until they are just starting to color, 4 to 7 minutes. Add the garlic and cook, stirring occasionally, for 4 to 6 minutes. Add the cocoa powder and chili powder and cook, stirring occasionally, until fragrant, about 2 minutes. 

Add the wine and cook, stirring to scrape up any browned bits. Add the tomatoes and orange juice, then return the pork to the pot. Cook over medium-high heat until the liquid is reduced by half, about 15 minutes. Add the stock and bring to a boil, then reduce to a simmer and cook until the pork is tender. Adjust the seasoning with salt.

To prepare the yams, in a large sauté pan, melt the butter. Add the onions and cook, stirring occasionally, until starting to soften. Add the yams, then add the chile powder, cumin, cinnamon, cloves and allspice. Cook, stirring occasionally, until fragrant, 2 to 3 minutes. Add just enough water to cover the yams and cook until the yams are tender. 

Transfer the yam mixture to a blender or food processor and blend until smooth. Add the cream and season with salt.

Transfer the pureed yams to a whipped cream canister and dispense according to the manufacturer's instructions. Serve with the pork stew.