3 medium oranges prepared according to illustrations below to make 1 1/2 cups
5 teaspoons lime juice from 1 to 2 limes
1/4 teaspoon Dijon mustard
1/2 teaspoon ground coriander , toasted in small dry skillet until fragrant, about 30 seconds
1/8 teaspoon table salt
Ground black pepper
3 tablespoons vegetable oil
5 radishes , quartered lengthwise and cut crosswise into 1/8-inch-thick slices (about 1 1/3 cups)4 ounces baby arugula (about 4 cups)
Place orange pieces in nonreactive mesh strainer set over bowl; let stand to drain excess juice. Meanwhile, whisk lime juice, mustard, coriander, salt, and pepper to taste in large bowl until combined. Whisking constantly, gradually add oil.
Add oranges, radishes, and arugula to bowl and toss gently to combine. Divide arugula among individual plates, place a portion of oranges and radishes over arugula, and drizzle with any dressing in bowl; serve immediately.