2 tablespoons canola oil
1 (2-lb.) boneless pork shoulder roast (Boston butt), trimmed
1 tablespoon kosher salt, divided
1 teaspoon freshly ground black pepper
2 tablespoons minced garlic
1 1/2 tablespoons chopped fresh rosemary
1 1/2 tablespoons chopped fresh oregano
6 medium shallots, halved lengthwise
1/4 cup unsalted tomato paste
1 cup dry red wine
2/3 cup unsalted chicken stock (such as Swanson)
2 tablespoons Dijon mustard
1 (28-oz.) can unsalted whole peeled plum tomatoes, undrained
3 cups stemmed chopped lacinato kale
1 tablespoon red wine vinegar
8 cups water
2 cups stone-ground polenta