In a 10-inch skillet over medium-high heat, heat the oil. Add the ground pork and a pinch of salt. Cook, stirring often, until fully cooked, about 4 minutes. Remove and set aside.
In the same skillet, add mushrooms, onions, and carrots. Cook for 2 minutes, stirring occasionally, until slightly softened.
Add garlic and ginger. Cook for 30 seconds, stirring constantly.
Add spinach, soy sauce, vinegar, and black pepper. Cook, stirring, until the spinach wilts.
Return the pork to the skillet and stir to combine.
Serve over rice.
Notes
Prep Ahead: Chop all ingredients before cooking, stir fries come together fast.
Use Any Vegetables: Zucchini, broccoli, squash, or bell peppers all work well.
Pick the Right Pan: A 10-inch skillet works best. Too large and the sauce cooks off; too small and cooking slows down.
Try Other Meats: Ground beef, turkey, or chicken are great substitutes.
Go Meatless: Omit the meat for a hearty vegetable stir fry.