Bring a large pot of water to a boil. Place the first 7 ingredients in a small bowl and whisk to combine (does not have to be completely smooth). Heat the oil in a large wok or skillet set over medium-high heat. Add the onion, tofu and garlic and stir-fry 2 to 3 minutes. Meanwhile, place the noodles in the boiling water and cook 60 seconds, or until tender, and then drain well.
Add the soy sauce mixture to the wok or skillet and bring to a simmer. Add the noodles and green onion and toss to combine. Divide the Pad Thai among bowls. Divide and top with bean sprouts and peanuts. Garnish with cilantro sprigs and lime slices and serve.
Note: Use a wider type of rice noodle for this dish if available. Package sizes can vary. If the size you bought contains more than you need for this recipe, wrap and keep the remainder for another time. Roasted peanuts are available in the bulk foods section.