Combine soy sauce, ginger, beef stock, and vinegar in a mixing bowl. Whisk vigorously while slowly pouring sesame oil in the mixture.

Heat vegetable oil in a large saute pan or wok. Add beef. Season easily with salt, but with lots of black pepper. Pre-ground black pepper will save alot of work, but grinding your own peppercorns will intensify the flavor!

Remove beef. Set aside. Add pepper and onions. Saute on high heat. Add garlic when veggies are nearly tender and cook until golden brown.

Add sauce mixture. Return beef. Toss to incorporate.

Whisk cornstarch and cold water together to make a slurry. Toss and stir beef vigorously while adding slurry to avoid lumps.

Cook for one minute to remove starchy taste and allow cornstarch to reach thickening potential.

Garnish with scallions and toasted sesame seeds.

Variations; Lemongrass, peppercorn melange, basil, eggplant, squash, sake, mirin, Worcestershire, hoisin, oyster sauce

Tip: An egg white in a meat marinade can add a nice shine