BEEF: In a large bowl, combine steak, salt, pepper, 2 teaspoons cornstarch, and sesame oil; toss to coat, set aside while you make the sauce and spiralize the zucchini noodles.
SAUCE: In a medium bowl, whisk together soy sauce, Hoisin, chili sauce, garlic, ginger, and 3 tablespoons cornstarch; set aside.
Spiralize the zucchini noodles using a spiralizer or a vegetable peeler.
Add 2 tablespoons vegetable oil to a large skillet over medium-high heat until pan starts to get smoky. Add beef sear and brown on both sides, about 1-2 minutes. (You may have to cook in batches depending on the size of your pan.) Transfer seared beef onto a plate.
Return pan to heat and add pineapple chunks, cook until caramelized, about 1-2 minutes. Stir in carrots, beef and sauce .Allow the sauce to bubble and thicken. Slowly add reserved water as needed if sauce is too thick.
Add the zucchini noodles to the pan, using tongs quickly toss to coat with sauce. Cook for 1-2 minutes until zucchini is just tender but still firm. Be careful not to overcook. Serve immediately garnished with green onions and sesame seeds.
Cook’s Notes: Do not overcook the zoodles or they will get soft and mushy. You can also serve the beef over raw zoodles if desired.