In your small bowl, whisk together all the sauce ingredients – soy sauce, hoisin, rice vinegar, ginger, garlic, cornstarch, and any other optional boosters. Whisk until the corn starch is completely dissolved (no lumps!) Set this flavor powerhouse aside. (Pro tip: doing this first prevents frantic measuring later and ensures smooth sauce.
Heat one tablespoon of neutral oil in your large skillet or wok over medium-high heat (you want it hot). Add the ground beef. Cook, breaking it up constantly with your spoon or spatula for 5 to 6 minutes until it's nicely browned and no pink remains. Drain off most of the excess fat (leave about 1 teaspoon for extra flavor). Transfer the cooked beef to a clean bowl.
Don't wash the pan! add the one tablespoon of toasted sesame oil to the same skillet (the residual beef bits add flavor!). Immediately add the diced onion and bell Peppers. Stir-fry for 4 to 5 minutes only. You want them vibrant, slightly softened, but still crisp-tender! no soggy Peppers allowed. (Pro tip: high heat + quick cook = fresh flavor and texture!).
Push the veggies to the sides of the pan, creating a well in the center. If using fresh ginger and garlic, add them to the center now. Stir constantly for 30 seconds until incredibly fragrant (don't burn!). If using powdered ginger/garlic, add it directly to the veggies now and stir for 15 seconds.
Add the cooked beef back into the skillet with the veggies and aromatics. Stir everything together for 1 minute, letting those flavors mingle.
Give your pre-mixed sauce another quick whisk (cornstarch settles). Pour it evenly over the beef and pepper mixture. Still constantly! Bring it to a simmer. You will see the magic happen: the sauce will bubble, turn glossy, and thicken beautifully within two to three minutes, coating every morsel perfectly. Remove from heat.
Divide the warm, fluffy rice among the deep bowls. Generously pile the saucy, glistening beef and pepper mixture on top.
Scatter sliced green onions and toasted sesame seeds generously over each bowl. Serve immediately with lime wedges on the side. Instruct everyone to squeeze that lime over their bowl before eating. (This is the key! The bright acidity cuts the richness and makes all the flavors pop).