1. Heat a griddle pan until smoking. In the meantime make the marinade for the greens. In a shallow bowl mix together half the olive oil and za'atar. Add the zest of the lemon and mix well.
2. Add the asparagus and broccoli and roll in the marinade. Make sure you use the florets to mop up any left over spice flavour.
3. Lay on the griddle and allow to cook for a few minutes before moving them around to char on all sides.
4. Make the salad by tossing together the watercress, spinach and capers.
5. Squeeze in a little lemon juice, the remaining olive oil and balsamic vinegar.
6. Toss the salad together before tasting and adjusting the seasoning with salt and pepper.
7. Serve the salad piled high topped with the griddled greens and a generous sprinkling of freshly grated parmesan. Drizzle with a little extra olive oil and balsamic vinegar for the perfect Summer salad.