1. Preheat the oven to 400 degrees.
2. Pulse flour and butter in a food processor until crumbly. Add 2 tablespoons of water, and pulse for 30 seconds or until dough forms a ball.
3. Turn out dough ball on lightly floured surface. Roll into flat sheet and press into dough tart pan. Prick bottom of crust with a fork. Refrigerate for 30 minutes before baking.
4. Remove shell from refrigerator and bake at 400 degrees for 15-20 minutes, or until crust is golden.
5. Dough can be made up to 2 days ahead and kept chilled, or frozen for up to 1 month.

Directions for Tart Filling:

• Lower oven temperature to 350 degrees.
• Cut mushrooms into thin strips.
• Heat saute pan. Add olive oil and heat on medium-high. Add mushrooms when oil is hot (you should hear a sizzle when they hot.) and saute until the mushrooms are tender and lightly browned, stirring occasionally. (If your pan is not hot enough, the mushrooms will steam and not be at their optimum.) Cool mushrooms.
• Spread onion jam on the tart shell. Evenly layer the cooked mushroom strips over the jam. Shave or grate the Nettle Jack over the mushrooms.
• Bake at 350 degrees for 10 minutes or until tart is warmed and cheese is melted.
• Let stand for 5 minutes then zest (or finely grate) fresh lemon peel over the top just before serving. Serve warm.