Slice the pork thin: Freeze the pork for 15 minutes so it firms up. Slice against the grain into thin strips.
Pat dry and season lightly with salt and pepper.
Whisk the sauce: In a small bowl, mix sweet chili sauce, soy sauce, lime juice, rice vinegar, sesame oil, and optional heat. Stir in the cornstarch slurry until smooth. Set aside.
Prep the veggies: Keep everything bite-size and uniform for fast, even cooking.
Separate scallion whites and greens.
Heat the pan: Use a large nonstick skillet or wok over medium-high. Add oil and swirl to coat until shimmering.
Sear the pork in batches: Add half the pork in a single layer. Sear 1–2 minutes per side until just browned.
Remove to a plate. Repeat with remaining pork. Do not overcrowd or it will steam.
Stir-fry aromatics: Lower heat slightly if needed.
Add garlic, ginger, and scallion whites. Stir for 30 seconds until fragrant.
Add veggies: Toss in broccoli, bell pepper, onion, and carrot. Stir-fry 3–4 minutes until crisp-tender.
Splash in a tablespoon of water if the pan gets dry.
Combine and sauce: Return pork (and any juices) to the pan. Pour in the sauce and toss to coat. Cook 1–2 minutes until the sauce thickens and glazes everything.
Finish and serve: Remove from heat.
Sprinkle scallion greens and sesame seeds. Taste and adjust with a squeeze of lime or a pinch of salt. Serve over your base of choice.