Heat a small skillet over medium heat and toast walnuts. Shake the pan a few times. Walnuts are down when they start to smell toasty and color on the edges. The walnuts can go from toasty to burnt in a split second so be sure to keep your eye on them while they are on the heat. Remove from heat and set aside.
In a small bowl or canning jar, combine red wine vinegar, honey, olive oil, and ground coriander. Stir or shake to combine. Set aside.
Using a mandolin, holding the carrots lengthwise, thinly slice carrots.
Next, thinly sliced radishes.
Cut scallions into thin slices on the diagonal.
Place slices of carrots, radishes and scallions on a platter.
Drizzle with dressing and top with nuts. Season with salt and pepper.