Start by draining the tofu and pressing it to remove excess moisture. Wrap the tofu in a clean kitchen towel and place a heavy object on top for about 15 minutes.
Once pressed, cut the tofu into bite-sized cubes. Smaller pieces will become crispier when cooked.
In a bowl, toss the tofu cubes with 2 tablespoons of arrowroot powder and a pinch of salt to coat them evenly.
Heat 2 tablespoons of cooking oil in a large non-stick skillet or wok over medium-high heat. Add the tofu cubes in a single layer without overcrowding the pan.
Fry the tofu for about 5-7 minutes, flipping occasionally until golden brown and crispy on all sides. Remove from skillet and set aside.
Add remaining tablespoon of cooking oil to the skillet. Sauté minced garlic and ginger for about 30 seconds until fragrant. Add broccoli florets and stir-fry for 3-4 minutes until bright green and slightly tender.
In a small bowl, mix white vinegar, water with veggie bouillon paste, soy sauce, fermented black bean sauce, and sugar to create the sauce.
Pour the sauce over the broccoli and stir to coat. Add crispy tofu back to the skillet along with toasted sesame oil and green onions. Stir together for 2-3 minutes until heated through.
Serve the stir fry hot over a bed of warm cooked brown rice, garnished with extra green onions if desired.