Heat barbecue to high. Poke potatoes a few times with the tip of a knife and microwave on HIGH for 2 min. or until slightly softened. Slice into 1/2-in. (1 cm) thick rounds. Grill 5 min. on each side or until golden and crisp.
Arrange arugula in a shallow serving bowl. Top with potato slices. Add dressing and toss to combine. Garnish with blue cheese and chives.