- from Richard, after Cynthia J suggested it

6 tablespoons fresh lime juice

1 medium large tomato cored, seeded, cut into a 1/4 inch dice

1/2 small red onion cut into a quarter inch dice

1 serano pepper

thyme (to taste)
1/4 bunch bitter herbs, diced (dandelion greens or arugua)
1 tablespoon olive oil

salt:  3/4 teaspoon

dice mushrooms into quarter inch pieces

marinade mushrooms in lime juice for one hour

(Used a non reactive bowl.  mix frequently)

Mix all ingredients, serve