Gather all your ingredients for sautéed mushrooms.
Use a slightly damp paper towel to brush off any dirt on the mushrooms.
Remove and discard the mushroom stems, then thinly slice the mushroom caps.
Add the olive oil and butter to a frying pan placed over medium high heat.
Add the mushrooms and sauté, stirring occasionally, until they start to release their juices.
Stir in the garlic and oregano and cook for another minute or two.
Stir in the salt (if using) and pepper, adding more or less according to your personal preference.
Place the cooked mushrooms in a decorative bowl.
Sprinkle the chives on top of the mushrooms.
Leftover sautéed mushrooms will keep in the refrigerator for a few days and can be re-heated in a microwave or small sauce pan.