Finely grind 5 ounces (150 grams) peeled and toasted almonds in a food processor for 5 minutes (this sounds like a long time but is necessary to achieve the right texture). Scrape the walls of the food processor from time to time and grind until a smooth paste is obtained. Add 8 ounces (250 grams) cold butter, cut into cubes, to the almond paste, and process the mixture until it is perfectly homogeneous. Season with salt. The butter can be used as is or made perfectly smooth by working it through a fine-mesh drum sieve with a plastic pastry scraper or rubber spatula. This butter is excellent on grilled fish and vegetables.