Add flour to large bowl. Using a grater, grate frozen butter into flour mixture. Gently toss to coat.

Add water evenly over butter/flour mixture and stir using fork until incorporated.

Form into a large square and wrap in plastic wrap. Allow to chill for about 30 minutes.

Remove from refrigerator. Over a floured surface, begin rolling out the dough with a rolling pin, until it forms a large rectangle.

Arrange dough with a short side nearest you, then fold dough into thirds like a letter: bottom third up and top third down over dough.

Rewrap and chill another 30 minutes.

Repeat rolling out, folding, and chilling steps twice more. Then allow to chill for about 1 hour.

Preheat oven to 375F

On a floured surface, roll the dough out into a circle.

Press dough firmly into a 8-10 inch tart pan. Trim excess around edges.

Spread 1 tablespoon of whole grain mustard evenly onto bottom of tart.

Sprinkle crumbled cheese evenly across bottom of pan.

Next, evenly spread out the sliced tomatoes. It is best to use tomatoes of varied sizes to help fill in the tart pan as much as possible.

Sprinkle tart with fresh herbs and a pinch of sea salt.

Bake at 375F for about 45 minutes, or until crust is a golden brown color.

Garnish with any remaining fresh herbs and microgreens. Can be served warm or chilled.