Step 1Preheat oven to 180°C. Line a large baking tray with baking paper. Combine 1 teaspoon miso, 2 teaspoons mirin and 1 teaspoon olive oil in a large bowl. Add sweet potato, toss to coat, and transfer to prepared tray. Roast for 25–30 minutes, or until golden and tender.
Step 2Heat a barbecue hotplate or chargrill pan to medium-high. Lightly spray the steaks and asparagus with oil. Grill steaks for 2–3 minutes each side, for medium, or until cooked to your liking. Transfer to a plate, cover loosely with foil and rest for 5 minutes. Grill the asparagus for 1–2 minutes, turning, or until lightly charred and just tender.
Step 3Mix the remaining miso, mirin, olive oil and the lemon juice in a bowl until well combined.
Step 4To serve, divide the baby spinach, sliced cucumber, radish, roasted sweet potato and asparagus between 4 serving bowls. Thinly slice the beef steaks and add to each salad bowl. Drizzle with the miso dressing and garnish with toasted sesame seeds.