"To steam the potatoes" means to cook them by placing them in a container above boiling water so that the heat from the steam cooks them thoroughly. Full definition
Steam the potatoes in 1 inch of boiling water for 20 minutes and then remove from heat. (onnit.com)
* I had a made some mashed potatoes with just steamed potatoes and some grass - fed butter a couple days prior and used this as a base for my pancakes. (macrobalanced.com)
In a blender, put steamed potatoes, yogurt, eggs, sugar, rice flour or powdered milk, and vanilla extract and mix well. (innerharmonynutrition.com)