Prep the vegetables: slice scallions, julienne the carrot, and thinly slice the bell pepper. Grate zucchini and squeeze it dry.
Whisk flour, sweet rice flour, salt, and pepper in a large bowl.
Pour in the ice-cold water and whisk just until smooth and no dry spots remain.
Fold in the scallions, carrot, zucchini, bell pepper, and garlic until evenly coated.
Heat 1 tbsp oil in a large nonstick skillet over medium-high heat.
Spoon about 3/4 cup batter into the skillet and spread into a thin round.
Cook until the edges crisp and the bottom turns golden, 3 to 4 minutes.
Flip, press lightly with a spatula, and cook 2 to 3 minutes more until browned and cooked through.
Transfer to a rack and keep warm. Repeat with remaining batter, adding more oil as needed.
Cut pancakes into wedges and serve hot with dipping sauce (see notes).