Heat a skillet over medium heat. Drain the tofu and cut it into 1/2 inch pieces. Add a small amount of oil to the pan, and fry the tofu until it is crisp around the edges. Remove from heat and keep off to the side.
While the tofu is cooking, bring a large pot of water to a boil. Add salt, and the pasta, cooking three minutes less than the package directions. Add the vegetables and cook until the pasta is al dente and vegetables are tender. About three more minutes.
Drain vegetables and pasta, reserving 1/2 cup of pasta water.
In a large bowl, whisk together the peanut butter (microwaving it for 10 to 30 seconds makes this easier), brown sugar, rice vinegar, soy sauce, sesame oil, garlic cloves, and red pepper flakes. Add the pasta, vegetables, and tofu to the peanut butter sauce, adding a little pasta water at a time if it needs to be thinned out.
Top with sesame seeds, and serve either warm or chilled, it's very good either way!