Slow Cooker Pork Tinga

vegetable oil

boneless pork shoulder or country style pork ribs, cut into 1-inch pieces (fat trimmed)

Yukon gold potatoes, peeled and cut into 1/2-inch pieces

medium yellow onion, cut into 1/4-inch slices

garlic cloves, minced

diced tomatoes with chipotle peppers

Worcestershire sauce

dried oregano

Salt and pepper,

Crumbled queso fresco, for garnish

Diced ripe avocado, for garnish