Citrus Braised Pork Tacos

2 tablespoons vegetable oil
1 onion, chopped fine
3 garlic cloves, minced
1 teaspoon ground cumin
1 teaspoon dried oregano
1/2 teaspoon ground cinnamon
6 oz. can tomato paste
1 1/2 cups water
1/4 cup frozen orange juice concentrate, thawed
3 tablespoons distilled white vinegar
1 1/2 tablespoons Worcestershire sauce
5 bay leaves
Salt and pepper
3 pound boneless pork butt roast, trimmed and cut into 1-inch chunks

Pickled Red Onions
1 red onion, halved and sliced thin
1 cup distilled white vinegar
1/3 cup sugar
1/4 teaspoon Salt

PICKLED RED ONIONS: Place onion in medium bowl. Bring vinegar, sugar,
and salt to simmer in small saucepan over medium-high heat, stirring occasionally, until sugar dissolves.
Pour over onions and cover loosely. Let onions cool completely, about 30 minutes.

PORK: Adjust oven rack to lower-middle position and heat oven to 300 degrees.
Heat oil in Dutch oven over medium heat until shimmering.
Add onion and cook until lightly browned, 4 to 6 minutes.

Add garlic, cumin, oregano and cinnamon and cook until fragrant, about 30 seconds.
Stir in tomato paste and cook, stirring constantly, until paste begins to darken, about 45 seconds.
Stir in water, orange juice concentrate, 2 tablespoons vinegar, Worcestershire, bay leaves,
2 teaspoons salt, and 1 teaspoon pepper, scraping up any browned bits.

Add pork and bring to boil. Transfer to oven, uncovered, and cook until pork is tender,
about 2 hours, stirring once halfway through cooking.

Transfer pot to stove and discard bay leaves. Using potato masher, mash pork until finely shredded.
Bring to simmer over medium-high heat, then reduce heat to medium-low and cook until most of liquid has evaporated, 3 to 5 minutes.

Off heat, stir in remaining 1 tablespoon vinegar and season with salt and pepper to taste.
Serve on tortillas with pickled red onions and lime wedges.