In a bowl, combine hoisin sauce, soy sauce, tomato paste, and Sriracha sauce, if using. Set aside.

Cut tofu in 1-cm (½-in.) thick slices; then cut each slice into two triangles.

Place tofu triangles and 125 mL (½ cup) of reserved sauce in a freezer bag.

Marinate in fridge from 15 minutes to 24 hours. Stir gently a few times while marinating.

Bring a large saucepan of salted water to a boil.

Blanch vegetables, one variety at a time, from 30 seconds to 2 minutes depending on their size.

Vegetables should be crisp. Drain in a colander. Spread vegetables onto a dish to let cool as needed.

In a large non-stick skillet, brown tofu triangles in oil over medium-high heat for 2 minutes on each side.

Do not overcook tofu or it will dry out quickly. Cook in two batches if necessary. Keep warm on a dish covered with aluminum foil.

Add blanched vegetables to skillet and sauté for 2 minutes over high heat until warm.

Cook in two batches as needed and set aside in a large bowl. Add soy sauce and mix gently to combine.

Divide vegetables onto each plate, add four tofu triangles on each serving of vegetables, and garnish with green onions and sesame seeds.

Drizzle with reserved sauce.