1. Preheat grill to 350° to 400° (medium-high) heat. Brush onion with 1 Tbsp. oil. Grill onion, covered with grill lid, 6 minutes on each side. Grill sausage 4 minutes on each side; slice.
2. Brush pizza crust with 1 Tbsp. oil. Grill crust, oil side down, 2 minutes. Turn crust over, and brush with 1 Tbsp. oil; sprinkle with cheese and 1/4 tsp. salt. Grill 2 minutes or until cheese melts.
3. Toss together arugula, parsley, pepper, sausage, onion, and remaining 1 tsp. salt. Top pizza with salad; squeeze lemon juice over salad. Serve immediately.