In a large mixing bowl, combine the thinly sliced flank steak with soy sauce, rice vinegar, sesame oil, baking soda, and black pepper. Toss well to ensure all beef is coated. Cover and refrigerate for at least 30 minutes, or up to 2 hours.

In a medium saucepan, whisk together soy sauce, rice vinegar, granulated sugar, honey, mirin, cornstarch, and 1/2 cup water until smooth. Add the minced ginger and garlic. Heat over medium heat, stirring constantly, until the sauce thickens and comes to a gentle boil (about 3-5 minutes). Remove from heat and stir in the sesame oil. Set aside.

In a shallow dish, whisk together cornstarch, all-purpose flour, salt, and white pepper. In another shallow dish, whisk the egg with 1/2 cup cold water.

Heat 3-4 cups of vegetable oil in a wok or large heavy-bottomed skillet over medium-high heat to 350-375°F (175-190°C).

Working in batches, dip each strip of marinated beef first into the egg wash, ensuring it's fully coated, then dredge it thoroughly in the flour mixture, shaking off any excess. Carefully place coated beef strips into the hot oil, ensuring not to overcrowd the pan.

Fry for 2-3 minutes per batch, turning occasionally, until golden brown and crispy. Remove fried beef with tongs or a slotted spoon and place on a wire rack set over paper towels to drain excess oil. Keep warm while you fry the remaining batches.

Once all beef is fried, add the crispy beef to the saucepan with the prepared ginger-garlic sauce. Toss gently to coat all the beef evenly.

Serve immediately over steamed rice or noodles, garnished with fresh julienned ginger, sliced green onions, and toasted sesame seeds.