Preheat oven to 425F.
In a large mixing bowl, place flour and salt.
Mix in butter by pinching between fingers until the texture becomes like coarse oatmeal.
Make a well in the centre of the mixture and add the egg and water.
Bring dough together, not over mixing.
Wrap and place in refrigerator for 15 minutes to rest.
Slice tomatoes and basil and set aside.
Once dough is rested, roll out dough to 1/8 “ on a floured surface.
Transfer to tart pan with removable bottom and trim off excess dough.
If making a “galette” style tart, roll out dough to 1/8” in a large circle.
Transfer to a parchment lined baking sheet.
Spread an even layer of mustard over the base of the tart.
Allow to sit a few minutes to dry out.
Arrange tomatoes over the mustard in a single layer, then drizzle with olive oil (and honey if using).
Sprinkle over fresh herbs, salt and pepper.
Layer goat cheese on top.
If making a “galette”, gather the edges to envelope the contents.
Bake for 20-30 minutes, or until dough is baked and tomatoes are tender.