(See Cooking tip.) Preheat the oven to 220C, fan-forced. Line 2 oven trays with baking paper. Pat the pork belly dry with paper towel. Rub with 2 tsp olive oil and season with salt and half the Tuscan seasoning.
Step 2 — Roast pork belly
Put the pork, skin-side up, on a lined tray and roast for 40 mins or until the skin starts to blister. Reduce the heat to 180C and roast for a further 25 mins or until the pork is cooked through. Rest for 10 mins.
Step 3 — Prep vegetables
Meanwhile, halve the unpeeled sweet potato lengthwise and put, cut-side down, on a chopping board. Put a skewer or chopstick on either side of the sweet potato to prevent cutting all the way through. Using a sharp knife, cut the sweet potato widthwise at 3mm intervals, without cutting all the way through. Quarter the onion lengthwise. Crush or finely chop the garlic.
Step 4 — Roast vegetables
When the pork has roasted for 30 mins, put the sweet potato and onion on the remaining lined tray. Combine the garlic and 2 tsp olive oil in a bowl and brush over the vegetables. Scatter with the remaining Tuscan seasoning. Roast the vegetables on the lower oven shelf for 35 mins or until golden and tender. Drizzle the onion with 1 tsp balsamic vinegar.
Step 5 — Make salad
Just before serving, thinly slice the apple. Put the apple, spinach and walnuts in a large bowl. Add the maple and mustard dressing and toss to coat.
Step 6 — Get ready to serve
Slice the pork. Divide the pork, sweet potato, onion and salad among plates. Drizzle the pork with any resting juices to serve.