2 cups thinly sliced red onion (about 1 large)
3 large navel oranges (about 5 pounds)
3 cups thinly sliced fennel bulb (about 1 pound)
1/4 cup loosely packed fresh mint leaves
3 tablespoons plain fat-free yogurt
2 tablespoons frozen orange juice concentrate, thawed
2 tablespoons red wine vinegar
1 teaspoon coriander seeds, toasted and crushed
4 teaspoons extravirgin olive oil 1/2 teaspoon sea salt
1/4 teaspoon freshly ground black pepper
Place thinly sliced red onion in a medium bowl; cover with ice water, and soak 15 minutes. Drain well.
Carefully remove rind and white pithy part of rind from oranges; discard rind and pith. Cut each orange in half vertically; remove white pithy core portion, and discard. Cut oranges crosswise into 1/4-inch-thick slices, reserving about 1/3 cup juice for dressing.
Layer red onion, thinly sliced fennel, and orange evenly in a bowl or on a platter, and sprinkle with fresh mint leaves. Combine reserved juice, plain fat-free yogurt, juice concentrate, and remaining ingredients in a small bowl, and stir with a whisk to combine. Drizzle evenly over salad; serve immediately.