Prepare the sauce: In a small bowl, whisk together the soy sauce, rice vinegar, sriracha, and cornstarch. Set aside.
Heat the avocado oil in a large, deep skillet (or wok) over medium-high heat. Add the pork strips and the onions and stir-fry until the meat is no longer raw, 5-7 minutes.
Add the pepper slices, garlic and ginger and cook, stirring, 1 minute.
Give the sauce a quick additional mix (the cornstarch tends to settle in the bottom). Lower the heat to medium and stir the sauce into the skillet. Cook, stirring, until the sauce thickens, about 3 minutes. As soon as it has thickened, remove the skillet from the heat.
Transfer the pork stir-fry to a serving platter. Drizzle with sesame oil, sprinkle with sesame seeds, and serve.
If the skillet becomes too dry at any point during cooking, add a splash of water.