Stir together first 8 ingredients; remove 1/2 cup mustard mixture. Cover and chill remaining mustard mixture 4 hours.
Stir together 1/2 cup mustard mixture and cubed chicken in a bowl; cover and chill 4 hours.
Remove chicken, discarding marinade. Thread chicken onto skewers, alternating with bell pepper.
Grill, covered with grill lid, over medium-high heat (350° to 400°) 12 minutes or until done. Serve with remaining mustard mixture.