Vegan Mushroom and Fried Tofu Sisig

Name: Vegan Mushroom and Fried Tofu Sisig
Ingredients: ½ cup olive oil, divided; 6 large (6 ounces total) fresh king trumpet mushrooms, cut into small cubes (about 6 cups); 4 cups fresh shiitake mushrooms (from 2 [3 1/2-ounce] pkg.), cut into small cubes (about 2 cups); 18 ounces firm fried tofu (from 2 [12-ounce] pkg.), cut into small cubes (about 4 cups); ¼ cup plus 2 tablespoons sherry vinegar; 4 pepperoncini salad peppers, sliced into thin rings (1/3 cup), plus more for garnish; 1 (4-inch) piece fresh ginger, peeled and minced (1/4 cup); ¼ cup light soy sauce; 3 large garlic cloves, minced (2 Tbsp.); 2 teaspoons granulated sugar; 2 teaspoons kosher salt; 2 fresh Thai red chiles, unseeded and finely chopped (1 teaspoon); ½ teaspoon black pepper; 2 cups diced red onion (from 2 medium [8-ounce each] onions); ¼ cup vegan mayonnaise; ¼ cup fresh lime juice (from 2 limes) or calamansi juice (from 1 [10-ounce] container); 3 scallions, sliced into 1/8- x 1/16- x 2 1/2-inch thin matchsticks (1/4 cup), plus more for garnish