Vegan Lemon Bars

This Lemon bar is a little creamier in texture than I can remember lemon bars being... but that's likely because I always liked the filling more than the crust, and also because I liked lemon curd more than lemon bars... so I've tweaked and combined techniques and come up with a lemon bar that reflects those tastes. the end result is a light creamy yellow sweet treat that bites the back of your cheeks with tang. Yum!

Filling: 

2 cups instant mashed potato flakes (make sure not flavored, not even butter)
2 cups vanilla soymilk
Zest and juice of 4 lemons
4 tablespoons margarine
2 cups granulated sugar
1/4 cup powdered sugar (or, if your like me and are making fudge at the same time, 3 oz. ricemello crème)
1 cup water
3 Tbs. agar agar flakes

Crust: 

2 sticks margarine (room temp)
2 cups flour
1 cup powdered sugar
Combine and stir potato flakes and soymilk in a large microwave bowl. Heat for about 1 minute until starch absorbs liquid. Stir in the margarine, letting it melt with the residual heat. Mix in the lemon juice and sugar and microwave for 45-1 min. It should still be lumpy. Throw in a blender or food processor with lemon zest and powdered sugar (or ricemellow crème) until smooth and creamy. Refrigerate for 4 hours (or overnight)
Mix the margarine, flour and powdered sugar together with your hands until smooth. Grease 9x13 pan and press dough into the bottom. Bake at 350 degrees for 10-15 minutes until edges slightly brown.
Soak agar flakes in water for 15 minutes in heavy saucepan. Bring to boil and dissolve agar agar. Turn off heat and mix in lemon mixture until completely combined. Pour lemon mixture over crust in pan and refrigerate for a few hours until firm,
Sprinkle powdered sugar on top, cut and serve.