Soak the noodles in a shallow dish covered in water until pliable, about 10 minutes. Mix the fish sauce and sugar in a small bowl and reserve.
Heat about 1 inch of vegetable oil in a high-sided skillet or wok and add the tofu. Fry the tofu until golden brown on all sides. Remove to paper-towel-lined plate to drain.
In the same pan, add the shallots and saute until translucent, about a minute. Crack in the egg and break up while stirring together. Mix in the reserved fried tofu, fish sauce and sugar mixture and noodles. If the noodles are not coated enough in the sauce, stir in a couple more tablespoons of fish sauce. Add in the green onions and saute for another 30 seconds. Add the bean sprouts and remove from the heat. Top with crushed peanuts, radishes, limes and chili powder.