1. Preheat oven to 325 degrees F. Put the tofu slices on a nonstick cookie pan. Add the soy sauce, trying to keep it on the tofu as much as possible. Bake for about 45 minutes, turning occasionally and adding more soy sauce if they look like they can absorb more.
2. When they are brown and dry, cut them into strips, about the size of French fries. You will need one strip per spring roll. (If you don't have time to bake the tofu, cut it into strips and fry it with the soy sauce on a nonstick skillet for a few minutes, carefully turning each strip, trying to crisp it up a little on each side.) Set aside.
3. Throw the rice vermicelli into boiling water and cook until just done, about 2 or 3 minutes. Pour into a colander, and rinse with cool water. The noodles need to be well drained and cool enough to handle. Set aside. Put 1-2" water in a pan that is big enough to hold the spring rolls.
4. Separate the wrappers, and stack them in the water, making sure each one is completely covered with water before putting in the next one. Leave the wrappers in the water until they are flexible (about 2 or 3 minutes). Remove the whole stack at once, and place them on a clean wet kitchen towel, covering them with another damp towel.
5. Now you are ready to assemble them. Carefully remove 1 wrapper and put it on another surface (I use a bamboo sushi mat, but you could easily use another damp towel. Working quickly, put onto the wrapper 3 or 4 small pieces of lettuce, 4 leaves mint, a handful rice noodles, 1 strip tofu, and a few tablespoons carrots, if desired.
6. Quickly fold the bottom of the wrapper over the pile, fold in the sides, and continue to roll up. After 4 or 5 are done, wrap each in plastic wrap to keep them from drying out too much. If one of them is falling apart, wrap it in plastic wrap immediately.
7. For sauce, combine vegan sugar, soy sauce, and broth. Bring to a boil. Crush the garlic with the salt. Mix the corn starch and cold water, add, and stir until the mixture thickens some. Simmer, stirring for 1 minute. Stir in garlic. Serve any temperature.
Serve spring rolls cold or room temperature with sauces of your choice. Do not cook these spring rolls. When you finish rolling them up, they are done! They will keep in the refrigerator for a day or two. They travel well for lunches and outings. For an appetizer, serve one or two per person. As a main course, count on at least three per person.