Low-Carb Vegetable Soup

Ingredients 2 tablespoons canola oil 1 (5 ounce) package sliced fresh shiitake mushrooms ½ cup chopped scallions, plus more for garnish 2 tablespoons Thai red curry paste, plus more to taste 1 ½ tablespoons grated fresh ginger 4 cloves garlic, minced 8 cups reduced-sodium vegetable broth 3 cups cauliflower florets (3/4-inch) 1 large zucchini, sliced…