I want to learn how to make a basic foam sauce, appreciate your sharing?
Thanks and good days....
1) Add some agar or gelatin to your sauce base. Strain through fine sieve. Use a whip cream whipper to foam it as needed.
2) Add some lecithin to the sauce base. Beat it with a mixer or blender. Skim off the foam to use as a sauce.
Gelatin and agar agar form a network that enables significant air entrainment. They also do a good job stabilizing the foam.
Lecithin is an emulsifier that collects at the air-water interface of the bubbles and stabilizes the foam somewhat.