Place sweet potato slices on a baking paper-lined baking tray. Lightly spray with oil and season with pepper. Bake in a 220C preheated oven (fan-forced) for 20-25 minutes, or until tender.
Meanwhile, to make gremolata, heat oil in a medium non-stick frying pan over a medium-high heat. Add asparagus, garlic and capers.
Cook, stirring, for 2 minutes, or until asparagus is bright green and just tender. Transfer to a medium bowl. Cool 10 minutes. Add parsley, macadamias, lemon rind and juice. Toss gently.
Add salmon to same frying pan. Cook for about 3 minutes each side, or until cooked to your liking.
Divide sweet potato and salmon among 4 plates. Spoon over gremolata. Serve with lemon wedges.

To toast macadamias, bake on a tray in 180C oven for about 5 minutes or until lightly golden. Replace with almonds, pistachios or pine nuts, if preferred.
White fish fillets can be used in place of salmon.