Combine all the ingredients for the dressing and whisk together. Set aside.
Thinly slice/shave the shallots and the bulb of the fennel (discarding the stalks but keeping the fronds). Finely chop the fronds to make 2 tablespoons.
Dice the jicama into quarter-inch cubes.
In a bowl, combine the shallot, fennel, jicama and fennel fronds. Toss with the dressing. Let marinate for roughly 15 minutes. (You can use this time to peel and slice the oranges.)
Add the orange slices to the salad and toss once more. (For a fancier presentation, cover a plate with the orange slices and top with the fennel mixture.)