Mix the flour, butter, salt and cardamom. Add water and mix until it becomes a ball. Be careful not to overmix.
Heat oven to 350 degrees.
Flour surface and rolling pin. Roll dough to 1/4 inch. thick and place into a 9 inch. pie pan. Crimp the edges and line crust with foil to maintain shape. Bake for about 20 minutes. Remove foil and continue to bake for an additional 5 minutes. Remove and let cool.
Crush 2 cups of the salmonberries through a sieve to remove the seeds. Add water to the salmonberry juice to make 1 1/2 cups liquid. Put the juice into a pot and add sugar and salt.
Mix the cornstarch and the cardamom with some of the juice, then add it to the sieved berry mixture. Cook on medium stirring constantly for about 5-10 minutes. Be careful not to scorch to bottom of pot. Remove from heat and let cool.
Add remaining berries, stir and pour into the pie crust. Chill until completely cooled. Serve with whipped cream.