For the cauliflower puree: Cook the cauliflower in salted boiling water until tender, about 10 minutes. Drain the water and transfer cauliflower to a blender. Add butter and blend until smooth. Season with salt and pepper. Keep warm.
For the pesto: In a blender, combine olives, basil, parsley, Parmesan cheese, 1/4 cup almonds, and olive oil. Season with salt and pepper. Transfer to an airtight container and keep refrigerated until ready to use.
For the grilled sardines: In a skillet, grill sardines in olive oil for 1 minute on the skin side. Season with salt and pepper. Keep warm.
For the serving: Pour some cauliflower puree on the bottom of a plate, top with 3 sardine fillets. Garnish each sardine with a dollop of the green pesto. Crush the remaining almonds sprinkle. Drizzle with some good olive oil and serve.
You can replace sardines with smelt, herring or mackerel.