In a mixing bowl, combine chicken broth, crushed black pepper, brown sugar, Worcestershire sauce, soy sauce, tomato paste, and cornstarch. Set aside.
Heat a pan over medium heat and add avocado oil, chopped onion, and minced garlic.
Saute until onion turns soft.
Add the prepared liquid mixture and stir continuously until the sauce reaches a smooth, glossy consistency.
Remove from heat and enjoy!
Notes
Use freshly crushed black peppercorns for the best aroma and flavor. For substitutions, swap chicken broth with beef broth, vegetable broth, or water; use canola, vegetable, or peanut oil instead of avocado oil.
Adjust the heat easily: use ½ teaspoon black pepper for mild heat, 1 teaspoon for medium heat, or increase to 1½–2 teaspoons with red pepper flakes for extra spice.
For restaurant-style results, slice beef, chicken, or pork thinly against the grain and coat with cornstarch, soy sauce, and oil before stir-frying.
Store cooled Chinese black pepper sauce in an airtight container in the refrigerator for up to 5 days. Freezing is not recommended because cornstarch may separate after thawing.
Reheat gently over low heat and add a splash of chicken broth or water if the sauce becomes too thick. Use it for stir-fries, noodles, rice, seafood, or vegetables.