For vegan masa, place chilled margarine into a mixing bowl and whip for 2 to 3 minutes until light and fluffy.
Add masa and beat for 1 minute.
Add vegetable stock a little at a time to mixture. Add salt and mushroom powder and beat for 4 to 5 minutes, or until a pinch of masa floats to the surface of a cup of water.
To make tamale filling, peel and cut potato lengthwise into 1/4-inch (French fry style) strips.
Heat pan with olive oil. Add potatoes and fry for 20 minutes, or until they turn brown.
In a food processor combine jalapeños, garlic, pine nuts, cilantro, olive oil and salt to form pesto for tamale filling.
Soak corn husks in hot water for about 15 minutes. Clean off any debris and silk.
To assemble the tamales, spread masa in a thin layer on the husk from the wide end of the husk across and down about four inches from the top.
Place four to five potato strips on top of the masa. Fold both ends of the husk over each other, then fold the bottom half up to meet the top.
Place tamales open end up in a large steamer pot with 3 to 4 inches of water under the tamales.
Bring the water to a high boil. Reduce to a medium high heat, cover the pot and steam for 50 minutes. Serve.