Preheat oven to 400F. Line 2 baking sheets with foil. Toss 1 medium cauliflower, cut into bite-sized pieces, with 2 tbsp olive oil, 1 tsp coriander, 1/2 tsp cumin and 1/4 tsp each cardamom and salt on 1 prepared sheet. Spread in a single layer (it’s okay if they touch). Bake in bottom third of oven until edges are golden, stirring halfway through, about 30 min. Arrange 4 salmon fillets, about 180 g each, skin-side down, on second prepared sheet. Sprinkle with 1/2 tsp salt. Season with fresh pepper. Brush 4 tsp apricot jam over tops of salmon. Sprinkle 1/3 cup coarsely chopped pistachios over salmon, pressing gently so they stick. Bake in top third of oven until a knife tip inserted into thickest part of fish comes out warm, 14 to 16 min.