Step 1 Preheat oven to 160°C. Spray an 8-cup-capacity ovenproof dish with a light coating of olive oil. Layer slices of potato, pumpkin, fennel, zucchini and tomato in prepared dish, sprinkling thyme between layers and finishing with a layer of potato slices.
Step 2 Pour vegetable stock carefully over vegies. Cover dish with foil and bake for 1 hour. Remove foil, sprinkle veg with parmesan and bake (uncovered) for 15–20 more minutes, or until surface is golden and veg are tender when pierced with a skewer. Remove dish from oven; leave to rest for 5 minutes.
Step 3 Meanwhile, combine mustard and chopped parsley in a small bowl. Set a large non-stick frying pan over high heat and spray with olive oil. Add steaks and cook for 2–3 minutes per side. Turn steaks and spread mustard mixture onto cooked sides; cook for another 2–3 minutes, or until done to your liking. Remove steaks from pan, cover loosely with a sheet of foil to keep warm and leave to rest for approximately 3 minutes.
Step 4 Divide mustard steak and vegie bake among serving plates, top veg with baby rocket and serve.