Lay the bound bundle of mustard greens on a cutting board. Cut off about 1 to 2 inches of their stems with a sharp knife. This makes individual leaves more uniform and removes the part that's a bit too tough to eat.

Fill a large bowl with cold water. Remove the rubber band holding the leaves together and gently submerge the leaves, pressing them all entirely under the water. Slowly and briefly swish them around.

Lift the mustard greens completely out of the water and pour out the water. Don't pour it out with the leaves still in the bowl or pour over the leaves, as this reintroduces the removed particles onto them. Rinse out the bowl.

Refill the bowl with cold water and repeat the process until you no longer see any dirt or debris in the water you pour out. Sometimes the greens come clean with one or two washings, other times you may need three or more, depending on how the mustard greens were handled and stored prior to your purchase.

Dry the greens in a salad spinner. If you don't have one, lay out a strip of paper towels on your kitchen counter. Place the leaves on top in a single layer, and then roll up the paper towels snugly around each leaf individually. Gently roll the bundle back and forth on the counter. Keep it in the refrigerator as is for up to a few hours; for storage of up to a few days, line a sealable plastic bag with new paper towels, remove the leaves from the bundle, place them in the bag and close it securely.

Fill a large saucepan with more than enough water to cover the mustard greens. Salt the water to taste with anywhere from a pinch to a tablespoon or so, bring it to a boil over high heat, and then reduce the heat to medium-high.

Dump the leaves into the pot and stir them gently with a cooking spoon to submerse them. Boil them for about one to two minutes, until they've just begun wilting. Drain the mustard greens in a colander, emptying the saucepan of the water, and press down on the leaves gently to release retained water. Chop the leaves into smaller pieces, if you want.

Place the empty pot back on the burner and coat the bottom with cooking oil. Drop in a pat or two of unsalted butter and chopped garlic, shallot or onion. Saute for about five minutes with other desired herbs and spices, such as salt, white pepper, turmeric, coriander, curry powder, a chili pepper powder, thyme, basil, sage or rosemary.

Return the mustard greens to the saucepan and stir them into the other ingredients well. Add in a small splash of red or white wine, stock, cider vinegar or other liquid, if you like, for extra flavor. Saute for another few minutes or more, until the leaves reach the desired texture; the longer you cook them, the softer and milder they become.