Press the extra-firm tofu for a minimum of 15 minutes to extract moisture, then cube into 1-inch pieces.
Dust the tofu cubes with cornstarch in a mixing bowl until a light, even coating is achieved.
Combine peanut butter, soy sauce, rice vinegar, sweetener, ginger, garlic, and warm water in a small vessel; whisk until an emulsified sauce forms.
Heat vegetable oil in a large non-stick skillet over medium-high heat until shimmering.
Sauté tofu cubes in a single layer for 8 to 10 minutes, rotating frequently until all surfaces are golden brown and crispy.
Steam the broccoli and carrots separately until they reach a tender-crisp texture.
Reduce skillet heat to low, pour the peanut sauce over the crispy tofu, and toss continuously for 60 to 90 seconds until the sauce thickens and glaze adheres.
Portion the cooked rice into four bowls, top with equal parts steamed vegetables and glazed peanut tofu.