Step 1Sift the flour and salt into a large mixing bowl. Toss the butter and the shortening with the flour until the cubes are coated. Use your thumbs and fingertips to crumble the butter and shortening into the flour, lifting the pieces and letting them fall back down.
Step 2Continue until the mixture resembles coarse cornmeal. Add the water a little at a time, and stir just until the mixture comes together.
Step 3Gather the dough together and knead briefly on a lightly floured board until it forms a smooth ball. Chill at least 2 hours before rolling out.
Step 4On a lightly floured surface, roll the dough to one-fourth to one-eighth inch, large enough to fit a 10-inch pie pan.
Step 5Line the pie pan, trimming the edges so that an inch hangs over the edge of the pan. Fold the overlapping dough up onto the edge of the pie pan, and press the excess into the inside of the pan to make a flat, thick shelf, with the edge of the dough even with the rim of the pan. Refrigerate for 30 minutes.
Step 1Caramelize the onions and garlic by cooking them in the vegetable oil with the salt and sugar in a medium skillet over low heat until golden brown, about 20 to 25 minutes.
Step 2Spread the onion mixture and the salmon over the bottom of the pie shell.
Step 3Beat the eggs in a bowl with the cream until blended. Season with salt and pepper. Pour over the onions and salmon, and bake in a 350-degree oven until puffed and browned, about 40 to 45 minutes.
Step 4Allow to stand for 10 minutes, then cut into slices. Sprinkle each slice with chives and serve.