In a small bowl, combine the olive oil, cumin, garlic, lemon zest and juice and natural yogurt. Set aside.
Steam the broccoli over a pan of boiling water for 3-4 minutes, until just tender. Add the asparagus for the final 2 minutes.
Toss together the salad leaves with the asparagus, broccoli, lentils and avocado. Divide between 4 plates, drizzle with the dressing and serve scattered with the seed mix.