Preheat grill or oven to 350 degrees F.
Place pork in a medium roasting pan. Stir together the stock, vinegar, BBQ sauce, jalapenos, onion, and garlic in a bowl. Pour the mixture over the pork and season with salt and pepper. Cover the pan with foil and cook in the oven or on the grill for 3 1/2 to 4 hours or until the meat is fork tender. Let cool in the braising liquid, then drain the liquid from the meat and shred the meat into bite-sized pieces. Serve on buns, drizzled with Black Pepper Vinaigrette.
Heat the oil over medium heat in a heavy-bottomed medium saucepan. Add the onion and garlic and cook until translucent, 3 to 4 minutes. Add the chili powders and cook for 1 minute. Add the tomatoes and water, bring to a boil, and simmer for 10 minutes. Add the remaining ingredients, except the peanut butter, and simmer for an additional 20 to 30 minutes or until thickened slightly, stirring occasionally. Transfer the mixture to a food processor with the peanut butter and puree until smooth. Season with salt and pepper, to taste. Pour into a bowl and allow to cool at room temperature.
Whisk together the vinegar, mustard, salt, pepper, and honey until combined. Slowly whisk in the oil until emulsified. Set aside until ready to use.