Preheat the oven to 400°F (200°C). Line a large baking sheet with foil. Spray foil lightly with cooking spray. Whisk miso with syrup and vinegar in a small bowl.
Trim off the tops of the eggplants and cut each one in half lengthwise. Brush cut sides with 1 tbsp (15 mL) of the oil and place cut side down on prepared sheet. Place salmon on prepared sheet. Roast 12 to 15 minutes or until salmon is just cooked and eggplant is tender.
Remove pan from the oven, position one rack just below the broiler and preheat the broiler.
Carefully flip eggplant so the cut sides are now facing up. Smear eggplant and salmon with a thin layer of miso mixture. Season with black pepper. Toss asparagus with remaining 1 tbsp (15 mL) oil and scatter around eggplant and salmon. Broil everything 2 to 5 minutes, watching carefully, until miso mixture becomes very dark brown in spots. Garnish with green onion.
Nutrients per serving: 440 calories, 34 g protein, 23 g fat (3 g saturated fat), 26 g carbohydrates (10 g fibre), 77 mg cholesterol, 675 mg sodium
Best Health tip: Look for miso in the refrigerated section of the grocery store. It keeps well in the fridge for many months.