Step 1 Preheat a barbecue (with a lid). Lay 4 squares of foil on a work surface. Prick potatoes all over and put each on a foil square; drizzle with olive oil and wrap in foil. Cook potatoes, turning occasionally, with barbecue lid closed, for 1 hour, or until tender.
Step 2 Meanwhile, combine yoghurt, mustard and dill in a small bowl; refrigerate until ready to serve.
Step 3 Put peach wedges and lemon, cut-side down, on barbecue; grill for 3–4 minutes, or until golden brown. Put grilled peach wedges in a large bowl. Squeeze warm lemon juice over peaches. Add zucchini, onion, walnuts, rocket and olive oil to bowl; stir.
Step 4 Unwrap baked potatoes with care, then cut a cross in top of each and open. Top potatoes with grilled-peach salad and a dollop of mustard yoghurt, and serve.