In a medium bowl, add 2 tablespoons of the Chinese black vinegar, the soy sauce, 1 tablespoon of the toasted sesame oil, the granulated sugar, 2 cloves of the garlic, the ginger, the black pepper, and 1/2 teaspoon of the ground Szechuan peppercorns and whisk until it is fully combined.
Reserve 1/2 of the marinade and set it aside.
In a medium bowl, add the steak slices and the remaining marinade and toss to evenly coat the steak slices.
Let the steak slices marinate at room temperature for 30 minutes.
Drain the marinade from the steak slices and pat the meat dry with a paper towel.
In a large bowl, add the marinated steak slices and the cornstarch and toss to coat, shaking off any of the excess.
In a large skillet, over medium-high heat, add 2 tablespoons of the peanut oil.
Working in 3 batches, add the marinated steak slices in a single layer to the heated oil and cook until they are seared, about 1-2 minutes per side.
Transfer the seared steak slices to a plate and cover to keep them warm. Repeat until all of the steak slices are seared.
Reduce the heat to medium.
In the same skillet, heat the remaining peanut oil.
Add the chili bean paste, the dried chilis, the remaining peppercorns, the remaining garlic, 3 of the sliced green onions, and the salt to the heated oil and cook, while stirring, until the mixture is fragrant, about 1-2 minutes.
Add the red chili oil and the bell peppers to the chili bean paste mixture and cook, while stirring occasionally, until the bell peppers have slightly softened, about 4 minutes.
Add the broth to the bell pepper mixture and cook, while stirring occasionally, until the bell peppers are tender, about 3-4 minutes.
Add the hoisin sauce, the sambal oelek, and the reserved marinade mixture to the bell pepper mixture and stir until evenly distributed.
Bring the sauce mixture to a simmer.
Add the cooked steak slices to the sauce mixture and toss to evenly coat.
Cook the stir-fry mixture, while stirring constantly, until the meat reaches an internal temperature of at least 135 degrees F for medium-rare doneness and the sauce thickens and clings to the steak slices, about 2-3 minutes.
Transfer the skillet from the heat.
Add the remaining toasted sesame oil and the remaining Chinese black vinegar to the stir-fry mixture and stir to combine.
Plate the stir-fry over the white rice.
Garnish with the sesame seeds and the extra green onions and serve.