Pat the pork cubes dry with paper towels. In a bowl season the pork with 1 tsp kosher salt, 1/2 tsp black pepper, and smoked paprika; toss to coat evenly.

Make marinade

In a separate bowl whisk together olive oil, soy sauce, apple cider vinegar, brown sugar, Dijon mustard, minced garlic, grated ginger, and red pepper flakes until sugar dissolves. Reserve 2 tablespoons of the mixture for finishing sauce.

Combine pork and marinade and let sit at room temperature for 20–30 minutes or refrigerate up to 2 hours. If refrigerated, bring to room temperature for 20 minutes before cooking.

Cook Pork & Vegetables

Sear pork

Heat a large heavy skillet or cast iron pan over medium-high heat until hot. Add 1 tablespoon neutral oil (use part of the olive oil from the marinade if desired). Working in a single layer, add half the pork cubes and sear undisturbed for 2–3 minutes until browned; flip and brown the other side 1–2 minutes. Remove to a plate and repeat with remaining pork. Do not overcrowd the pan.

Sauté aromatics and vegetables

Lower heat to medium. Add the sliced onion and carrots to the pan with a pinch of salt; sauté 3–4 minutes until edges soften. Add broccoli and sauté 2 minutes more. Push vegetables to the side.

Deglaze and simmer

Return all pork to the pan. Pour in the reserved marinade and 1/2 cup stock, scraping browned bits from the bottom with a wooden spoon. Bring to a gentle simmer, cover partially, and cook 6–8 minutes until pork is cooked through (internal temperature 145°F) and vegetables are tender-crisp.

Finish & Serve

Thicken sauce

Stir cornstarch into the 2 tablespoons cold water to make a slurry. Remove the pan from heat. Stir slurry into the pan sauce and return to low heat, simmering 1–2 minutes until sauce thickens and becomes glossy. Stir in sesame oil and the reserved 2 tablespoons of marinade if you didn’t add it earlier.

Taste and adjust seasoning with remaining 1/2 tsp salt and 1/2 tsp black pepper as needed. Garnish with sliced green onions and toasted sesame seeds. Serve immediately over steamed rice or noodles.