For the sauce: In a small saucepan bring the soy sauce, sugar and vinegar to a boil. Combine 3 teaspoons cold water and the corn starch in a small bowl to make a slurry. When the ingredients have come to a boil, whisk in the slurry. Cook the mixture for 1 minute, then remove from the heat and set aside.
For the vegetables: Heat 5 ounces vegetable oil in a saute pan until just hot, then remove the oil and keep the pan hot.
Turn the heat down to medium and place the marinated beef into the pan. Cook until just seared, then remove from the pan.
Add the remaining 2 teaspoons vegetable oil and the Sichuan pepper oil to the pan, then add the dried chiles.
Add in the onions, garlic and ginger, and saute until the onions are lightly wilted and the garlic and ginger are slightly caramelized.
Return the beef to the pan, and then add the sauce.
Serve with rice or noodles and seasonal vegetable of choice.