For the summer rolls: Bring a large pot of water to a boil. Add the mai fun noodles and cook until softened, 1 minute. With tongs, lift the noodles out of the water and drain; reserve the hot water for rehydrating the spring roll wrappers.
Lightly grease a baking sheet or serving platter with oil to prevent the finished summer rolls from sticking. Clear a large work surface in front of you. Along the far end of the surface, line up the spinach, enoki mushrooms, carrots, tofu, mint and mai fun in that order. Set the spring roll wrappers and reserved hot water to one side of you.
Take one spring roll wrapper and dip it into the hot water; it will soften quickly. As soon as the wrapper softens, lift it from the water and lay it flat and smooth on the work surface. Arrange 3 spinach leaves in a horizontal line across the center of the wrapper, leaving a 1 1/2-inch margin on either end. Top with a few pieces each of enoki and carrots. Place 2 or 3 pieces of tofu above the spinach, so the tofu and spinach lie parallel. Place 4 mint leaves above and parallel to the tofu. Top the carrots and mushrooms with about 1/4 cup of the mai fun.
Lift the end of the wrapper closest to you up and over the filling, tucking it slightly underneath with your fingertips. Gently shape the roll, giving a gentle tug to keep it taught. Begin rolling toward the back end of the wrapper, then fold the sides in toward the center of the roll to close off the ends. Continue rolling to the end of the wrapper. Place the summer roll on the oiled tray. Repeat to create 12 rolls.
For the peanut sauce: Whisk together the peanut butter, hoisin, soy sauce, sriracha, lime juice and garlic in a medium bowl. Whisk in 4 tablespoons water. The sauce should be a thick enough to coat the back of a spoon but still drip off lightly. Add another tablespoon or two of water if the sauce needs thinning.
For the nuoc cham: Whisk together the lime juice, fish sauce, sugar, sriracha, garlic and 3 tablespoons water in a small bowl. Refrigerate until ready to use.
Serve the summer rolls with the peanut sauce and nuoc cham.
Mai fun rice noodles and spring roll wrappers can be found at Asian markets or online.