- 20 garlic cloves, peeled
- 1 cup olive oil
- 1 pound skinless, boneless chicken breasts or thighs
- Kosher salt, freshly ground pepper
- 2 tablespoons Dijon or whole grain mustard
- 2 tablespoons red wine vinegar
- 1/4 cup pitted olives
- 4 cups (packed) arugula (not baby)
- 1/4 cup flat-leaf parsley leaves
- 3 roasted red peppers from a jar, cut into 1/2-inch-wide strips
- Set a fine-mesh strainer over a medium bowl. Bring garlic and oil just to a simmer in a small saucepan over medium-low heat. Reduce heat to low; cook, stirring occasionally, until garlic is golden brown and soft, 20-25 minutes. Let cool completely. Strain, reserving cloves and oil.
- Build a medium-hot fire in a charcoal grill, or heat a gas grill to high. Toss chicken and 2 tablespoons garlic oil in a medium bowl. Season with salt and pepper. Grill until charred and just cooked through, 4-5 minutes per side. Transfer to a board; let rest for 5 minutes.
- Purée 8 garlic cloves, 1/2 cup garlic oil, Dijon mustard, and vinegar in a blender or mini-processor. Season dressing with salt and pepper. Place remaining garlic cloves, olives, and remaining ingredients in a large bowl (cover and chill remaining oil for another use). Slice chicken on a diagonal; add to bowl. Spoon 2 tablespoons dressing over; toss. Serve with remaining dressing.