Directions

1. To prepare filling: Combine rice, thyme and 1/2 teaspoon salt in a large saucepan; add water and bring to a boil. Reduce heat to a gentle simmer and cook, uncovered, stirring occasionally, until the rice is a thick porridge, 45 minutes to 1 hour.
2. To prepare crust: Meanwhile, combine whole-wheat flour, all-purpose flour, thyme, 1/4 teaspoon salt, cayenne and mace (or nutmeg) in a medium bowl. Add 1/3 cup oil and 5 tablespoons water; stir with a fork until evenly combined. Knead the dough in the bowl a few times and pat it into a disk. Cover (or wrap in plastic) and refrigerate for at least 10 minutes and up to 1 day.
3. To finish the filling, heat 1 tablespoon oil in a large skillet over high heat. Add onions and cook, stirring, until lightly browned, 7 to 9 minutes. Reduce heat to medium. Continue cooking until the onions are golden brown, 5 to 10 minutes more. Add a few tablespoons of water, if needed, to release any bits that are sticking to the pan. Remove from the heat.
4. When the rice is almost done, position rack in lower third of oven; preheat to 350°F.
5. To assemble the pie: Coat a 9-inch deep-dish pie pan with cooking spray. Spread the rice porridge in the pan. Layer the caramelized onions and peas over the rice. Toss salmon and vinegar in a medium bowl. Layer the salmon on top of the peas.
6. Roll out the dough into a 12-inch circle and place on the pie. Trim the crust so it overhangs the pan by 1 inch; tuck the overhanging dough under and crimp the edges with a fork. Reroll the dough scraps and cut out a decorative salmon shape. Place it on top of the crust. Lightly brush the crust with egg white.
7. Bake the pie until the crust is golden, 40 to 50 minutes. Remove from the oven and cool for 10 minutes before serving.

Tips

• To make ahead: Prepare rice (Step 1) and dough for crust (Step 2), cover and refrigerate separately for up to 1 day.
• Equipment: 9-inch deep-dish pie pan