1 teaspoon coriander seeds, smashed in a pestle & mortar
Zest of 1 unwaxed lemon
Preheat oven to 200c fan-forced (220 non-fan). Line a baking tray with baking paper.
Dust work surface and pastry with flour, roll sheet to approx. 31cm x 31cm, cut sheet in half.
Place both pieces of pastry on baking tray lined with baking paper, place another piece of baking paper on top followed by a baking tray. Bake at 200c fan-forced (220 non-fan) for 10 minutes, reduce oven temperature to 180c fan-forced (200c non-fan) and continue to bake for a further 10 minutes. Remove top tray and baking paper and return to oven for a further 5-10 minutes until golden. Set pastry to one side.
Cut onions in half and slice thinly. Pour half the olive oil in a medium sized thick based pan, add onions and sprinkle over the sugar. Cook over low heat for 30 to 45 minutes or until soft. Remove from pan and set to one side (if there is a lot of liquid in the onions tip into a colander).
Wash spinach thoroughly and drain. Use the same pan you cooked the onions in, warm the pan over medium heat, add the remaining olive oil and sliced garlic followed immediately by the spinach (it will hiss & spit a bit), place a lid on the pan, after a couple of minutes the leaves should have begun to wilt, give them a toss in the garlicky olive oil and season with a little salt and pepper. Once all the leaves have wilted, remove from pan and strain in a colander.
When ready to serve, pre-heat oven to 180c fan-forced (200c non-fan). Place the two pieces of baked pastry on a baking tray lined with paper. Top the pastry with the spinach and onion. Crumble over the feta, then sprinkle the feta with the crushed coriander seed and grated lemon zest, drizzle with a small amount of olive oil, finish with a grind of black pepper. Place in the oven for 15 to 20 minutes or until the feta starts to turn golden.
Tip: The beauty of this tart is the components can all be made ahead of time, then simply combine and pop in the oven when ready to serve.