Red onion tart

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A ham and cheese sandwich generates 1.5 times more CO2e than a red onion tart, and a Cornish pasty generates 2.4 times more CO2e.

From Recipe from ‘Keep it Vegan’ by Áine Carlin.

Serves 4


  • one 35 x 22.5cm sheet ready-rolled puff pastry
  • 300 grams asparagus spears, halved lengthways olive oil juice and grated zest of
  • 1 lemon coarse sea salt
  • 4 red onions, finely sliced
  • 1 teaspoon dried thyme
  • 1 tablespoon sugar dash of red wine vinegar
  • salt and freshly ground black pepper
  • 450 grams frozen peas
  • 30 grams fresh mint leaves, roughly chopped


  1. Heat 2 tablespoons of oil in a non-stick frying pan. Add the onions and season. Sweat for several minutes, then sprinkle over the dried thyme and sugar. Once the onions begin to soften, add the red wine vinegar. Add a dash of oil if necessary and allow to sweat gently for 30 minutes until completely soft.
  2. Meanwhile, place the peas in a bowl of boiling water. After a few minutes, drain and place in a food processor with the mint, 2 tablespoons of oil and lemon juice. Season and blitz to form a coarse purée.
  3. Preheat the oven to 200˚C. Cut the pastry into 4 equal rectangles and place on baking trays.
  4. Leaving a 1cm border around the edge of each pastry rectangle, spread a quarter of the pea purée over each, followed by a quarter of the caramelised onions. Arrange the asparagus over the top. Drizzle with a little olive oil, season and bake for 25–30 minutes.
  5. Finish with the lemon zest, a fine sprinkling of freshly chopped mint and a pinch of coarse sea salt.
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