Combine apple cider vinegar, juice, tomato sauce, soy sauce, and salt in a small saucepan. Cook the sauce over low heat until it starts to bubble.
Meanwhile whisk cornflour and 2 tablespoons of water. Stir the cornflour mixture into the sauce and whisk, stirring the sauce vigorously for a couple of minutes until thickened.
Let the sauce cool at room temperature for a few minutes. Then stir in honey, mix well, and set aside.
Slice the green onions and cut mushrooms into halves. Peel and slice the carrot diagonally. Cut the peppers into strips.
Next heat oil in a wok or a skillet over medium-high heat. Add garlic and sauté until fragrant.
Add carrots, bell peppers, and broccoli florets. Cook, stirring constantly, until veggies are slightly golden brown, 3-4 minutes. Stir in the mushrooms and green onions and continue to stir fry for 2-3 minutes more.
Pour in the prepared sweet and sour sauce and bring to a boil, then toss to coat the veggies while still on the heat.
Remove from heat and serve hot. Enjoy!