Thoroughly wash the mustard greens: Rinse each leaf well, and then submerge under water in a large bowl or clean sink. Remove the leaves from the water and place in a colander. The grainy dirt that’s removed from the greens will accumulate at the bottom of the bowl. Rinse and refill the bowl, then repeat the process with the greens until there’s no remaining dirt. This normally takes 3 cycles.

Tear the mustard green leaves from the stems. Discard the stems, then roughly chop the leaves and place them in a large bowl.

Heat the olive oil in a Dutch oven or large, heavy skillet over medium-high. Add the onion and cook, stirring occasionally, until translucent, about 7 minutes. Add the garlic and cook, stirring often, for 1 minute.

Add the stock, 1 teaspoon salt, ½ teaspoon pepper and the chopped mustard greens to the pot. Bring to a boil and then reduce the heat to a hearty simmer. Cook, uncovered, until the greens are very tender and no longer bitter, 35 to 45 minutes.

Remove from the heat and stir in the hot sauce. Add the liquid smoke (if using): As the intensity of liquid smoke varies by brand, it’s best to add it gradually, tasting as you go, until it’s deliciously smoky but not overpowering. Season the mustard greens with more salt, if you like. Allow to cool slightly before serving. The greens are best the day they’re made.

Serve in bowls to savor the sauce.