01 - Heat a non-stick skillet over medium heat. Add sliced shiitake mushrooms and sauté for 5-6 minutes, stirring occasionally, until tender and lightly golden. Set aside to cool completely.
02 - Slice the avocado, julienne the carrot and cucumber, thinly slice the bell pepper, and finely chop the scallions. Arrange all prepared vegetables, spinach, and fresh herbs within easy reach for assembly.
03 - Fill a shallow dish with warm water. Dip one rice paper sheet in the water for 10-15 seconds until just pliable and softened. Carefully lay flat on a clean kitchen towel or cutting board.
04 - Place a small handful of spinach or lettuce in the center of the rice paper. Layer with avocado slices, sautéed shiitake mushrooms, carrot, cucumber, bell pepper, scallions, and fresh herbs. Fold the bottom edge over the filling, fold in both sides, then roll tightly from bottom to top to seal. Repeat with remaining ingredients to make 8 rolls.
05 - Whisk together soy sauce, rice vinegar, sesame oil, maple syrup, grated ginger, and minced garlic in a small bowl until smooth and well combined. Add water 1 teaspoon at a time to reach desired consistency.
06 - Serve spring rolls immediately, either whole or sliced in half diagonally, with the dipping sauce on the side. Best enjoyed fresh within 2 hours of preparation.