01 - Heat a non-stick skillet over medium heat. Add sliced shiitake mushrooms and sauté for 5-6 minutes, stirring occasionally, until tender. Set aside to cool.
02 - Slice avocado, julienne carrot and cucumber, thinly slice bell pepper, arrange spinach, scallions, cilantro, and mint 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 softened, then carefully lay flat on a clean kitchen towel or cutting board.
04 - Place spinach or lettuce in the center of the rice paper. Top with avocado slices, sautéed shiitake, carrot, cucumber, bell pepper, scallions, and herbs. Fold bottom over filling, fold in both sides, and roll tightly. Repeat with remaining ingredients to make 8 rolls.
05 - Whisk soy sauce, rice vinegar, sesame oil, maple syrup, grated ginger, minced garlic, and water in a small bowl until smooth. Adjust consistency with additional water if needed.
06 - Serve spring rolls immediately, whole or sliced in half, with dipping sauce on the side.