This spicy salpicon, a chopped topping that's similar to salsa, comes from chef Rick Bayless. It's part of his Cinco de Mayo guacamole bar. Get All the Recipes
Over a low gas flame or under the broiler, roast poblano peppers, turning frequently, until charred, about 5 minutes over flame or 10 minutes under broiler. Remove from heat and cover with a clean kitchen towel until cool enough to handle. Rub off charred skin using a paper towel; remove stem and seeds. Rinse pepper and pat dry; cut into 1/4-inch pieces and transfer to a medium bowl.
Place onion in a fine mesh strainer and rinse under cold water. Shake off excess water and transfer to bowl with peppers. Add mushrooms, oregano, and lime juice; season with salt. Cover and refrigerate until ready to serve.