Place 4 teaspoons of the Seasoning, 3 tablespoons of the oil and vinegar in large resealable plastic bag. Seal and shake to mix. Add veggies to bag, turning to coat well. Refrigerate 15 minutes or until ready to grill.
Remove veggies from marinade and place on grill over medium heat. Brush Halloumi with remaining marinade from bag and place on grill with veggies. Grill until veggies are tender and grill marks appear on Halloumi, turning occasionally.
Meanwhile, place arugula, Parmesan, pine nuts and remaining Seasoning in food processor or blender; cover. Process just until smooth. With center part of cover removed and blender running on medium speed, gradually add remaining oil just until blended. Cover blender completely. Blend on high speed until smooth.
Layer veggies and Halloumi on rolls and drizzle with pesto to serve.
Test Kitchen Tips:
• Halloumi cheese is a firm, salty cheese with a somewhat rubbery texture, traditionally made from goat and sheep’s milk. It is sometimes referred to as “grilling cheese” or “frying cheese” since it holds up well to high temperatures both on the grill or in a skillet. Look for it in the specialty cheese aisle in your grocery store or online. If you can’t find Halloumi, Indian Paneer is similar.
• Try to find portobello mushroom caps that are the same size as your rolls. If you can’t find the right size mushrooms, cut them to fit.