Clean the mushroom caps with a damp paper towel.

Remove the stems carefully.

Optionally, scrape out the dark gills for a cleaner look.

Whisk together olive oil, balsamic vinegar, soy sauce, garlic, smoked paprika, black pepper, and Dijon mustard.

Place cleaned mushrooms in a dish or bag and pour marinade over them, coating well.

Let sit for 15-20 minutes at room temperature, or up to an hour in the refrigerator.

Heat a cast-iron skillet over medium-high heat until hot.

Add a small drizzle of oil to the pan.

Place the marinated mushrooms cap side down and press lightly.

Cook undisturbed for 4-5 minutes until dark brown.

Flip mushrooms to gill side and cook for another 4 minutes, basting with leftover marinade.

Add a knob of butter if desired for extra juiciness.

Let mushrooms rest for 3-5 minutes before serving.

Garnish with fresh parsley before serving.

Serve whole or sliced, with sides as preferred.