Toss potatoes and 2 tablespoons of olive oil in a large bowl. Cover tightly with plastic wrap and microwave until edges of potatoes are translucent, 4 to 7 minutes, shaking bowl (without removing plastic wrap) to redistribute potatoes half way through cooking.
Meanwhile, in a large bowl, combine vinegar, garlic, sugar, salt and pepper. Slowly whisk in remaining oil until emulsified. stir in roasted red peppers, capers and parsley.
Grill potatoes until slightly charred and tender, about 5 minutes per side. Toss grilled potatoes with dressing to coat. Serve warm or room temperature.
Notes
This Recipe Can be Doubled: Simply increase the ingredients proportionately and cook in batches if necessary.
Add Bacon: Crumbled bacon makes everything better. Bacon-y flavor makes this salad sing.
Fresh Herbs: Top with fresh dill, chives in place of the fresh parsley, or do both.
Onion: Chopped green onion, red onion or shallots gives this warm potato salad additional flavor.
Alternate cooking method tip: Cook inside with a grill pan or large skillet for a great indoor picnic.