Mix the oregano, chipotle powder, cumin, salt and pepper together in a small bowl.
Season the cubed pork chunks with the spice mixture and put into a large Dutch oven. Add the onion, garlic, chicken stock, the tomato puree, honey, orange and lime juice, and the juiced orange and lime halves. Stir together with a wooden spoon. Put the pot on medium heat and bring the mixture to a simmer. Transfer to the oven and cook, covered, until the pork is tender and easily shreds, about 1 hour and 45 minutes.
Remove the meat from the Dutch oven to a cutting board. Set the Dutch oven over medium heat and reduce the liquid until it becomes slightly syrupy, about 10 minutes. Meanwhile, shred the meat and add to a bowl. Drizzle the reduced cooking liquid into the pork and toss. Serve with tortillas, cilantro, sour cream and Zesty Slaw.
Zesty Slaw:
Whisk the rice wine vinegar, lime juice, canola oil, and sugar together in a small bowl.
Add the cabbage, cilantro, green onions, and carrot to a large serving bowl and combine. Drizzle with the dressing and toss to coat. Season with salt and pepper, to taste, and serve.