Preheat oven to 400 degrees F. Line a baking sheet with parchment paper.

Combine olive oil, juice of 1 lemon, cumin, turmeric, coriander, garlic, paprika, salt, black pepper, and cayenne in a medium bowl. Pour ¼ cup of the sauce over the salmon, turning to coat. Let sit for 20 minutes.

Pour the remaining marinade over the sliced red onion and bell pepper, tossing to coat.

Meanwhile, make the rice. Melt butter in a medium saucepot over medium heat. Add garlic and saute for 30 seconds. Add rice, stirring to coat. Add chicken stock and bring to a boil. Cover the pot, reduce heat to low, and continue to simmer for 15-20 minutes or until the rice is tender and all the liquid is evaporated. Let sit for 5 minutes. Remove cover and fluffy rice with fork.

Spread seasoned vegetables and salmon on the prepared sheet pan. Bake for 17-20 minutes or until salmon flakes easily and vegetables are softened. Cut salmon into bite-size chunks.

Assemble bowls. Portion rice into bowls and top with salmon, roasted vegetables, tzatziki, feta, mint, dill, and a sprinkle of sumac. Serve immediately.