Step1. Preheat oven to 220°C/200°C fan-forced. Line a baking tray with baking paper. Place pumpkin, syrup and oil in a bowl. Toss to combine. Place pumpkin, in a single layer, on prepared tray. Season with salt and pepper.
Step2. Bake for 20 to 30 minutes, adding walnuts to tray for the last 8 minutes of cooking, or until pumpkin is tender.
Step3. Spray a frying pan with oil. Heat over medium-high heat. Cook chicken for 6 to 7 minutes each side or until cooked through. Transfer to a plate. Stand, covered, for 5 minutes. Thinly slice.
Step4. Meanwhile, make Mustard dressing: Place oil, vinegar, syrup and mustard in a screw-top jar. Secure lid. Shake to combine. Place pumpkin, walnuts, chicken, salad mix, onion and dressing in a bowl. Toss to combine. Serve.
Step5. You could use 1/4 cup pine nuts instead of walnuts. Add to salad with dressing in step 4.