Segment the oranges and cut each segment in half. Squeeze the juice from the oranges' membranes into a bowl. Whisk in the lime juice, coriander, cumin, 1/2 teaspoon salt and olive oil.
Gently toss the jicama, red onion and oranges with the lime vinaigrette and transfer to a serving bowl. Top with the avocado, cilantro and a sprinkle of salt.