I went through a phase where whenever I found Lactarius indigo growing I tried to come up with preparations that would keep their blue color. This is one of the more interesting ones: a blue mushroom vinaigrette.
It's not the type of vinaigrette you're going to throw on a salad, since you won't be able to enjoy the color, rather, it's meant for dressing something like a piece of fish or chicken, (poached or grilled would be great).
Keeping the color is key to making this look attractive. As I talked about in my recipe for preserving lactarius in oil, keeping the color of the mushrooms is done by exposing them to moist heat in combination with vinegar or citric acid. For our vinaigrette recipe, I found that allowing the mushrooms to macerate with the vinegar without any heat keeps the attractive color the best.
Does this mean that the mushrooms are raw and you have to be worried about eating them? Not at all. I've never had a problem eating lactarius indigo and the maceration process, although it doesn't involve heat still "cooks" the mushrooms and starts to break them down with the exposure to salt and vinegar.
It only takes a couple mushrooms to make a batch, and some that may have some damage will be fine, just make sure they're fresh, crisp, and most importantly still giving off their deep blue color when cut.
Lactarius Indigo Vinaigrette
- 1 cup vegetable broth preferably homemade
- 3 cups chopped fresh lactarius indigo mushrooms
- ⅓ cup mild olive oil
- ⅓ cup champagne vinegar
- Small clove of garlic minced
- 1 tablespoon shallot diced ¼ inch
- 1 tablespoon chopped fresh thyme
- 1 teaspoon kosher salt plus more to taste
- ¼ teaspoon ground white pepper optional
- In a small bowl, combine the shallot and garlic with the salt and pepper then allow to macerate for 15-20 minutes. Add the mushrooms, vinegar and thyme, and place the mixture in a food processor.
- Process the mixture, drizzling in some of the vegetable broth until you get a smooth puree. You may not need all of it.
- Finally, drizzle in the oil, still processing all the while.
- When all the oil has been added, double check the seasoning and adjust as needed, then transfer to an airtight container (a mason jar works great for vinaigrettes) and reserve until needed.