Tomato, shallot and mustard tart

Method

1. First, make the pastry. Sift the flour into a mixing bowl with the mustard powder and a pinch of salt, or simply whisk everything together well if you can’t be bothered with the sieve.
2. Add the butter and lard and rub everything together with your fingertips until it resembles coarse breadcrumbs, with a few pea-size bits of butter and lard still left in the mixture. Stir in the thyme. Gently whisk together the egg yolk and the iced water, trickle it over the flour mixture and cut it all in with a dinner knife to combine. You may need a splash more water – add it a little at a time, so you don’t use too much. Gently knead the pastry together into a ball with your hands, then turn it out onto a sheet of baking paper. Wrap and chill for at least 30 minutes.
3. Lightly dust a work surface with flour and roll out the pastry into a circle approx. 1cm thick. Line the tart tin with the pastry, letting any excess pastry hang over the sides, then chill again for 20 minutes.
4. Heat the oven to 180°C fan/gas 6. Prick the base of the tart all over with a fork, line with baking paper and fill with raw rice or ceramic baking beans. Put on a baking sheet and bake for 15 minutes, remove from the oven and carefully remove the paper and beans. Whisk the egg white with a little cream or milk, brush over the base of the tart case, then return the case to the oven to finish cooking completely for about 10 minutes. Remove and trim off the excess pastry.
5. Slice off the tops of the tomatoes, cut out the cores, then slice them quite thinly, to about the thickness of a pound coin. Put them in a colander over the sink, sprinkle with a little salt and leave so some of their liquid drains off.
6. Warm 2 tbsp of the oil in a frying pan over a low-medium heat, then fry the shallots with a pinch of salt until slightly softened, stirring from time to time, without letting them take on any colour (about 10 minutes).
7. Brush the base of the tart with the mustard, then spoon on the shallots. Layer on the tomatoes, scattering on the thyme as you go, along with a little salt and a few grinds of pepper. Trickle on the remaining olive oil. Put the tart tin on a baking sheet and bake for 25-30 minutes until the tops of the tomatoes begin to caramelise. Carefully remove the tin from the oven, sprinkle the parmesan over the top and return to the oven for a further 5-10 minutes. Serve warm or cold, with a green salad.