Combine soy sauce, chicken broth, vinegar, chili paste, sherry, and cornstarch in a large bowl. Mix until cornstarch is dissolved. Set sauce aside.
Heat oil in a large skillet over medium-high heat. Cook cauliflower until golden brown and charred in places, about 15 minutes. Reduce heat to low. Stir in the sauce and cook until sauce starts to thicken, about 2 minutes. Add peanuts and garlic and cook for 2 minutes more.
Transfer to a serving dish and garnish with green onion tops.