How to Make It
Pat tofu dry with paper towels. Place 7 teaspoons cornstarch in a large bowl. Add tofu; toss to coat. Remove tofu from bowl. Heat oil in a large nonstick skillet over medium-high. Add tofu; cook 6 minutes or until golden and crisp, stirring occasionally. Remove tofu to a plate with a slotted spoon.
Combine remaining 2 teaspoons cornstarch and 1/4 cup stock in a bowl, stirring with a whisk until smooth. Stir in remaining 3/4 cup stock, soy sauce, vinegar, and hoisin.
Add cauliflower to remaining oil in pan; cook 3 minutes or until lightly browned, stirring occasionally. Add celery and garlic; sauté 2 minutes. Add ketchup and pepper; cook 1 minute, stirring to coat. Add stock mixture to pan; bring to a boil. Cook 2 minutes or until liquid is slightly thickened. Add cooked tofu; toss. Top with green onions.