MIX mayo, chiles and garlic until well blended. Refrigerate until ready to use. Cut off ends of jicama; discard or reserve for another use. Cut remaining jicama lengthwise in half, then cut each half crosswise into 6 slices. Arrange cut ends of slices together on platter to form 6 circles.
HEAT oil in large skillet on medium heat. Coat fish with flour; shake gently to remove excess flour. Add to skillet; cook 6 to 8 min. or until fish flakes easily with fork, turning occasionally. Cool slightly; flake fish with fork.
TOP jicama with fish, tomatoes, onions, cilantro and mayo mixture.