Prepare Vegetables: Slice the courgette, aubergine, and onion. Quarter the potatoes and cut the red pepper into large pieces.
Marinate: Mix olive oil, crushed garlic, and soy sauce. Toss the vegetables in this mixture and let marinate for 15 minutes.
Make Ponzu Mayo: Combine ponzu sauce, mayonnaise, rosemary, garlic, and pepper. Mix well and chill.
Grill: Preheat the grill to medium. Cook vegetables for 7-10 minutes, turning occasionally. Potatoes may require 15-20 minutes.
Serve: Arrange grilled vegetables on a plate and serve with ponzu mayo on the side.