Remove the collard green leaves from the tough stems and discard the stems. Transfer the leaves to a large basin filled with water. Wash thoroughly, rubbing the leaves together to remove grit. Drain and repeat washing until the water runs clear.

Roll the cleaned leaves tightly and slice into thin ribbons using a sharp knife. Set aside.

Heat the olive oil in a large stockpot over medium-high heat. Add the chopped onion and cook for 2 to 3 minutes, until softened. Add the garlic and cook for 1 additional minute, stirring frequently, until fragrant.

Add the collard greens to the pot in batches, stirring after each addition to allow the greens to wilt. Season with smoked paprika, garlic powder, onion powder, cayenne pepper, red pepper flakes, salt, and black pepper.

Pour in 3 cups of vegetable stock, then add the vinegar and liquid smoke. Stir to combine. Bring the mixture to a boil, then reduce the heat to medium-low, cover, and simmer for 60 minutes, stirring occasionally.

If the liquid reduces too much during cooking, add additional vegetable stock as needed. Taste and adjust seasoning. Continue simmering for up to 30 additional minutes, until the greens are silky and tender.

Transfer the collard greens to a serving bowl with some of the cooking liquid. Serve warm, with hot sauce if desired.