Toast Sichuan peppercorns in a dry sauté pan over medium heat for a couple of minutes until aromatic. Let them cool slightly, then grind to a fine powder.

Heat a wok over medium-high heat. Add ground beef and soy sauce, cooking until browned, about 5-6 minutes. Break it apart for even browning.

Use a slotted spoon to transfer the cooked beef to a plate, leaving the flavorful fat in the pan.

In the same pan, add garlic and ginger; sauté until golden (about 1-2 minutes).

Toss in ground black pepper, half of the ground Sichuan peppercorns, broad bean paste, and black beans. Sauté for another 30 seconds.

Add chicken stock and sugar, scraping up any bits stuck to the bottom; return beef to the pan. Let it simmer for about 5 minutes.

In a small bowl, dissolve cornstarch in a few tablespoons of cold water to create a slurry.

While stirring the simmering sauce, pour in the cornstarch slurry and adjust thickness as desired.

Gently add tofu cubes into the sauce and let it simmer for about 5 minutes.

Transfer the Mapo Tofu to a serving bowl, drizzle with chili oil if desired, and garnish with chopped green onions and remaining Sichuan peppercorns.

Serve hot over a bed of fluffy jasmine rice.