Prepare grill to medium-high heat.
Drain sun-dried tomatoes in a sieve over a bowl, reserving oil. Place 1 1/2 tablespoons reserved oil in a blender or food processor. Coarsely chop 2/3 cup drained tomatoes; place in blender or food processor. Place remaining oil and tomatoes in sun-dried tomato jar; reserve for another use. Add broth and next 7 ingredients (through garlic) to blender or food processor; process until smooth.
Place chicken on grill rack coated with cooking spray; grill 5 minutes on each side or until done. Serve chicken over couscous; top with sauce.