In a large pot, combine the baby bella mushrooms with enough water to cover them. Add 1/2 cup white wine vinegar, cover and boil for about 5 minutes.

Remove the lid and boil uncovered for an additional 5 minutes to infuse flavor.

Drain the mushrooms using a colander and transfer them to a large mason jar while still hot.

In a mixing bowl, whisk together the remaining 1/2 cup white wine vinegar, olive oil, minced garlic, parsley, shallot, lemon thyme, oregano, ground pepper, and salt until well combined.

Pour the marinade over the hot mushrooms, seal the jar, and shake gently to distribute the marinade.

Let the jar cool to room temperature, then refrigerate for up to 1 week, shaking occasionally.