1. Prepare the stir-fry sauce by thoroughly mixing soy sauce, cornstarch, rice vinegar, chili garlic sauce, minced garlic, grated ginger, brown sugar, optional chicken broth, and sesame oil in a small bowl. Set the sauce aside.
2. Slice zucchinis into half moons or rounds, dice additional vegetables if using, mince more garlic and ginger for the pan, and slice pork tenderloin (if not using ground pork) into thin strips.
3. Heat a large pan or wok over medium-high heat with vegetable or peanut oil. Add the ground pork or tenderloin slices, season with salt and pepper, and cook for 5-7 minutes until browned. Transfer the cooked pork to a separate plate and set aside.
4. In the same pan, add more oil if needed. Add zucchini slices and optional vegetables, and stir-fry for 3-5 minutes until slightly charred but still crisp. Optionally drizzle with sesame oil for added flavor.
5. Return the pork to the pan and pour in the prepared stir-fry sauce. Stir everything together, ensuring all ingredients are well-coated. Let simmer for 1-2 minutes until the sauce thickens and becomes glossy.
6. Garnish with chopped green onions and sesame seeds for a fresh, bright finish.
7. Serve hot over cooked rice, noodles, or a low-carb option like cauliflower rice. Optionally, add lime wedges or Sriracha on the side for added flavor.