Choose your protein: For chicken — pat pieces dry and season lightly with 1/2 tsp salt and 1/4 tsp pepper. For tofu — press to remove excess water, then toss gently with 1/2 tsp salt. For squid — pat dry and season with 1/4 tsp salt.

Batter and coat (chicken or squid only)

In a shallow bowl combine 1 cup cornstarch, 1 tbs flour, 1 tsp salt, and 1 tsp pepper. Beat the egg in a separate bowl. Dip each piece of chicken or squid in the beaten egg, then dredge thoroughly in the cornstarch mixture, shaking off excess.

Fry protein (optional — for crispy texture)

Heat 1–1.5 inches of vegetable oil in a heavy skillet or wok to 350°F (medium-high). Fry coated chicken pieces in batches until golden and cooked through (about 4–6 minutes depending on size) and squid until just opaque and curled (about 1–2 minutes). Transfer to a paper-towel-lined plate. For tofu: shallow-fry cubes 2–3 minutes per side until golden, or pan-sear with 2 tbs oil until crisp.

Vegetables

Prep vegetables while oil heats: slice carrot, onion, broccoli florets, and red pepper into uniform pieces so they cook evenly.

Blanch broccoli (optional for brighter color): bring a pot of salted water to a boil, drop broccoli for 30–45 seconds, then transfer to ice water. Drain well.

In a large wok or wide skillet, heat 1 tbs oil over medium-high heat. Add minced garlic and minced ginger and stir-fry 20–30 seconds until fragrant. Add carrots and onions first and stir-fry 2–3 minutes until they begin to soften. Add red pepper and stir-fry another 1–2 minutes. Add broccoli and pineapple chunks and toss to combine; cook another 1–2 minutes so vegetables are crisp-tender.

Sauce

Make the sauce mixture: in a bowl combine 1 cup pineapple juice, 3 tbs rice vinegar, 1 tbs ketchup, 3 tbs brown sugar, 2 tbs soy sauce, and 1 tsp tomato paste (if using). Stir until sugar dissolves.

Create slurry: whisk 2 tsp cornstarch with 2 tbs cold water until smooth.

Pour the sauce mixture into the wok with the vegetables and bring to a simmer over medium heat. Stir, then slowly add the cornstarch slurry while stirring. Continue to cook 1–2 minutes until the sauce thickens to a glossy coating consistency.

Finish & Serve

Combine protein and sauce: add the fried or cooked protein (chicken, tofu, or squid) to the wok and toss gently so each piece is coated with sauce. Cook 1–2 minutes more so everything is heated through and flavors meld. Taste and adjust: add up to 1 tbs more soy sauce for salt, or 1 tbs more brown sugar for sweeter profile, or 1 tbs more vinegar for tang.

Garnish and serve: transfer to a serving platter, sprinkle sliced green onions and sesame seeds on top. Serve hot over steamed rice or noodles.