To make pomegranate glaze, combine pomegranate juice, sugar, lemon juice, and ginger in a medium saucepan. Bring to a boil over medium-high heat, stirring to dissolve the sugar.

Boil the pomegranate juice mixture until thick, syrupy and reduced to one cup, about 25 minutes. Remove from heat and allow to cool. (May be done up to one day in advance; refrigerate until needed.)

Make the salmon: preheat the oven to 450 degrees Fahrenheit and line a baking sheet with foil. Place the salmon fillets on the baking sheet, skin-side down. Pat dry and season with salt and pepper.

Measure out one-fourth cup of the pomegranate glaze. Brush each salmon fillet with approximately one tablespoon of the sauce. Roast the salmon until the center is opaque and flakes easily with a fork and the internal temperature reaches 125 degrees on an instant-read thermometer.

While the salmon is cooking, prepare cauliflower rice according to package instructions. Drain.

When the salmon is cooked through, remove the skin from the fillets. To serve, divide the cauliflower rice among four plates. Add a salmon fillet to each plate. Spoon approximately two tablespoons of the pomegranate reduction over each salmon fillet. (There will be sauce leftover.) Top with chopped walnuts and mint. Serve immediately.