Upside-Down Onion Tarts Recipe

<ul class="ingredients-main-list"><li class="ingredients-single-item">4 large onions (about 800g), thinly sliced</li><li class="ingredients-single-item">50g unsalted butter, plus extra for greasing</li><li class="ingredients-single-item">2 tbsp olive oil</li><li class="ingredients-single-item">1 tbsp balsamic vinegar</li><li class="ingredients-single-item">1 tbsp brown sugar</li><li class="ingredients-single-item">2 sprigs fresh thyme, leaves removed</li><li class="ingredients-single-item">375g ready-made puff pastry (or homemade rough puff pastry)</li><li class="ingredients-single-item">100g goat's cheese or crumbled feta (optional)</li><li class="ingredients-single-item">Sea salt and freshly ground black pepper, to taste</li></ul>

<ul class="equipment-main-list"><li class="equipment-single-item">6-hole muffin tin or 6 individual tart tins (10cm diameter)</li><li class="equipment-single-item">10cm round pastry cutter</li><li class="equipment-single-item">Heavy-based frying pan</li><li class="equipment-single-item">Baking paper</li></ul>

<ol class="no-list-style"><li class="MethodStepper"><h4 class="step-title">Step 1</h4>Preheat your oven to 190°C (170°C fan). Thoroughly grease 6 individual tart tins or a 6-hole muffin tin with butter, making sure to cover the base and sides well. This generous greasing is crucial as it will help release the tarts after baking and contributes to a beautifully golden exterior.</li><li class="MethodStepper"><h4 class="step-title">Step 2</h4>Heat a large, heavy-based frying pan over medium-low heat. Add the butter and olive oil, and once the butter has melted, add your thinly sliced onions with a pinch of salt. The salt will help draw out moisture and encourage caramelization. Cook gently for about 25-30 minutes, stirring occasionally. Be patient here – proper caramelization is slow and cannot be rushed. The onions should gradually turn a deep golden brown as their sugars develop and intensify.</li><li class="MethodStepper"><h4 class="step-title">Step 3</h4>When the onions have reduced significantly and turned a rich golden color, add the balsamic vinegar, brown sugar, and thyme leaves. The vinegar will deglaze the pan, lifting any flavorful browned bits from the bottom. Cook for another 5 minutes until the mixture becomes slightly sticky and deeply caramelized. Season generously with black pepper and adjust salt to taste. Remove from heat and allow to cool slightly.</li><li class="MethodStepper"><h4 class="step-title">Step 4</h4>On a lightly floured surface, roll out your pastry to about 3mm thickness. Using a 10cm round cutter, cut out 6 circles. The pastry may shrink slightly during baking, so ensure your circles are slightly larger than your tart tins.</li><li class="MethodStepper"><h4 class="step-title">Step 5</h4>Divide the caramelized onion mixture evenly among your prepared tins, spreading it to cover the base. If using cheese, crumble a small amount over each portion of onions. The cheese will add a lovely tangy contrast to the sweet onions.</li><li class="MethodStepper"><h4 class="step-title">Step 6</h4>Place a pastry circle on top of each filled tin, gently tucking the edges down around the filling. Don't press too firmly – just enough to create a seal. Using a sharp knife, make a small incision in the center of each pastry circle to allow steam to escape during baking. This prevents the pastry from becoming soggy.</li><li class="MethodStepper"><h4 class="step-title">Step 7</h4>Bake in the preheated oven for 20-25 minutes, until the pastry has risen and turned a beautiful golden brown. The edges should be crisp and deeply colored. A well-developed color means well-developed flavor in the pastry.</li><li class="MethodStepper"><h4 class="step-title">Step 8</h4>Remove from the oven and let the tarts rest in their tins for 5 minutes – this brief resting period helps them set and makes unmolding easier. Then, place a serving plate over the tin and carefully but confidently flip it over to turn out the tarts. The caramelized onions should now be on top, beautifully glazed and fragrant.</li><li class="MethodStepper"><h4 class="step-title">Step 9</h4>If any onions stick to the tin, carefully scrape them off and arrange them back on top of the tart. Serve warm or at room temperature, perhaps with a light green salad or a small dollop of crème fraîche. These tarts can also be made ahead and reheated in a moderate oven for 10 minutes before serving.</li></ol>