Sliced scallions or cilantro, for garnish
In a large bowl, combine the mushrooms, olive oil, lime juice, lemon juice, shallot, and garlic, and stir gently.
Season with salt and pepper.
Marinate in the refrigerator for at least 30 minutes, and up to 3 hours.
Taste and season again with salt and pepper, if needed.
Garnish with scallions and serve. VARIATION 1 SPICY MUSHROOM CEVICHE: Add ½ fresh jalapeño pepper (seeded and finely chopped) to the marinade. VARIATION 2 VEGGIE MUSHROOM CEVICHE: Add ½ sliced green bell pepper, ½ sliced red bell pepper, and 1 shredded carrot to the mushrooms and marinade. PREP TIP: You can leave these in the fridge for up to a day, so make them ahead of time if you want to get ahead on your meal or party planning.