Penang Pork Satay

Name: Penang Pork Satay
Ingredients: 2.5 inch piece turmeric root, peeled and sliced thinly across the grain; 1 teaspoon ground turmeric, or to taste; 1 (2 inch) piece fresh ginger root, sliced; 1 large shallot, roughly chopped; 8 cloves garlic, peeled, or more to taste; 0.25 cup light brown sugar; 3 tablespoons ancho chili powder; 2 teaspoons ground coriander; 1 teaspoon chipotle chili powder; 0.5 teaspoon cayenne pepper; 0.25 cup rice vinegar; 2 tablespoons soy sauce; 1 tablespoon fish sauce; 1 teaspoon tamarind paste; 0.5 bunch lightly packed cilantro leaves and stems; 1 (2 1/2 pound) pork shoulder roast; 1 tablespoon kosher salt; 5 large metal skewers