Boil he milk, cream, salt, pepper, sugar and lemon zest in a pot. Take it off the heat. Now add the gelatin and the horseradish.
Let the mixture be for 10-15 minutes, before sifting. Try it out for taste and pour into a siphon bottle.
Let the mixture rest for 6-7 hours, before pumping in the gas. Once that is done the whip is ready for consumption.