PREHEAT barbecue to medium. Boil a large pot of water. Soak 10 wooden skewers in warm water for 20 min.
STIR maple syrup with miso paste and rice vinegar in a small bowl until smooth.
BOIL brussels sprouts and radishes, cut in half, in a large saucepan of water until slightly tender, 3 min. Drain well. Pull out and discard stems from shiitake mushrooms. Pat dry and cut a tofu into 1-in. cubes. Cut 1 orange bell pepper into 1-in. pieces. Thread brussels sprouts, radishes, mushrooms, tofu and bell pepper onto skewers. Brush with sesame oil.
OIL grill. Barbecue skewers, lid closed, turning every 2 min, until grill marks form and vegetables are cooked through, about 8 min. Brush with miso-maple sauce.