A Cook's Plot

Vegetarian & Vegan

Red Onion Tart

I put in sets of the autumn-planted variety of red onion called ‘Electric’ at the allotment last autumn and they’ve been a big success (the first harvest is in the photo above). There’s no sign of onion rot on them - I’d read that planting them with mint can help keep this at bay so I sunk a lovely big pot of peppermint into the soil alongside them and it seems to have done the trick. I’m going to leave the mint there now - it smells fabulous when I water in the evening on these warm summer nights.

Usually ready in July, the onions were actually coming right up out of the ground by themselves by 20th June, so I laid them out in the sun for the skins to dry for a few days (which helps them to keep better). I couldn’t resist cooking with a few of them straightaway though, so when friends Liz and Nigel came to lunch last week, I made a red onion tart for them and served it with a mixture of lettuce leaves from the shady wall trough here and a potato salad made with chives from the garden. A wonderful lunch together on a perfect June summer’s day. Bliss!


  • 4 sprigs rosemary
  • 150ml milk
  • knob of butter
  • 5 red onions, sliced
  • 1 tsp caster sugar
  • 225g plain flour
  • 110g cold butter, chopped
  • 2 eggs
  • small grating of nutmeg
  • 2 tbsp balsamic vinegar


Strip the leaves from the rosemary sprigs and put in a small pan with the milk, then heat until almost boiling and set aside. Melt the butter in a wide-based pan, add the onions with 2 tbsp water and a pinch of salt, put a lid on the pan and cook gently for about 45 minutes until meltingly soft. Meanwhile, make the pastry by whizzing the flour, butter and a tsp of salt in a food processor until it resembles breadcrumbs. Add enough cold water, a tbsp at a time, until it starts to come together as a dough and then tip out onto a work surface and bring together lightly with your hands. Chill for 15 mins then roll out and line a loose-bottomed flan tin. Bake blind (see The Fig Tarts recipes in a previous post for how to do this) for 10 mins at 180C fan oven, then remove the baking beans and bake for a further 5 mins until base is just turning golden.

Take the lid off the onions and cook for a few minutes more over a higher heat to evaporate some of the liquid, then stir in the vinegar. Put in a jug with the milk (strain out the rosemary first), eggs, nutmeg and plenty of seasoning, then pour into the tart case and bake for about 30 mins until the filling is set and golden brown.

A Cook's Plot Tip

If you use a whole nutmeg for this (my preference), run the grater over one side about three times to get the right amount. If you use ground nutmeg, it's about quarter of a teaspoon.

My Latest Recipes