2. To prepare the dough: mix the flour and yeast in an airtight container, make a well in the middle and pour in the 100 ml of oil and hot water. Add a pinch of salt, close the container and shake horizontally and vertically.
3. Roll out the dough on a floured surface with a rolling pin (or a glass bottle). Line a tart pan with the dough and prick it with a fork.
4. Spread the mustard on the bottom and sides, arrange the slices of gruyère cheese, and the sliced tomatoes.
5. Season with salt and pepper, and drizzle with a little olive oil.
6. Bake in a hot oven (220 °C) for 35 to 40 minutes.
Notes & Suggestions
For those who know, the dough used is the famous Tupperware "minute dough". You can buy pre-made dough instead. But this dough can also be used as a base for other savory or sweet tarts.