Drain the tofu and use paper towels to press out any excess water. Cut into approximately 3/4-inch cubes and set aside.
Add 2 tablespoons coconut aminos, 2 teaspoons sesame oil, 1 tablespoon rice vinegar, minced garlic, grated ginger, white parts of green onion and red pepper flakes to a small bowl. Whisk to combine, and set sauce aside.
Heat a large skillet over medium-high heat. Add avocado oil and heat. Once oil is glistening, carefully add tofu cubes in a single layer. Drizzle on 1 tablespoon coconut aminos. Cook for 8 to 10 minutes, using tongs to flip every 1 to 2 minutes, ensuring even crisping on all sides.
Reduce heat to medium and pour in sauce. Let simmer for 2 to 3 minutes, carefully tossing the tofu to evenly coat.
Work in batches to add baby spinach and continuously stir until each batch is wilted.
Serve over a bowl of cooked cauliflower rice (optional). Garnish with remaining green onion and black sesame seeds (optional).