Begin with making the horseradish foam. Place the cream and grated horseradish in a saucepan over low heat. Bring to a simmer and cook for 3 minutes or until warmed through (be careful not to curdle). Use a fork to whisk in the soy lecithin until dissolved. Season with salt. Strain through a fine mesh sieve set over a large jug. Discard solids. Place in the fridge to coo