For the pickled onions: Combine sliced red onion, white wine vinegar, sugar, and 1/2 teaspoon salt in a bowl. Let sit at room temperature for at least 1 hour, stirring occasionally.

Season pork shoulder chunks with cumin, oregano, 1 teaspoon salt, and black pepper, rubbing the spices into the meat.

Place seasoned pork in a Dutch oven or heavy pot with garlic, bay leaves, orange juice, juice of 1 lime, and chicken stock. Bring to a boil, then reduce heat to low, cover, and simmer for 2.5 to 3 hours until pork is very tender and reaches an internal temperature of at least 75°C.

Remove pork from liquid and shred with two forks. Heat a large skillet over medium-high heat with 1 tablespoon oil and crisp the shredded pork for 8-10 minutes until edges are golden and caramelized.

For the sopes: Mix masa harina with warm water, remaining salt, and 2 tablespoons oil until a soft dough forms. Divide into 8 equal balls.

Press each ball into a 10cm disc about 1cm thick. Cook on a dry griddle or cast iron pan over medium heat for 2-3 minutes per side until lightly golden.

While still warm, pinch the edges of each sope upward to create a raised border, forming a small vessel for toppings.

Heat 1cm of vegetable oil in a skillet to 180°C. Fry each sope for 1-2 minutes per side until crispy. Drain on paper towels.

Warm the refried beans in a small saucepan over low heat, stirring occasionally.

Assemble sopes by spreading a layer of warm refried beans on each, then topping with crispy carnitas, drained pickled red onions, crumbled queso fresco, fresh cilantro, and avocado slices.

Drizzle with remaining lime juice and serve immediately with salsa verde on the side.