Peel the jicama and cut into spears. Peel the carrots and cut into sticks. Peel the oranges, then separate into sections. Cut 1 lime into wedges. Arrange the jicama, carrots and orange sections on a platter. Garnish with the lime wedges. Squeeze the juice from the other lime over the fruits and vegetables. Dust with chili powder and salt. Serve slightly chilled or at room temperature.