Heat a large sauté pan to medium heat, add oil and onion. When the onion is translucent and tender add the potatoes.
Cook for approximately 10 minutes or until the onion and potatoes are golden brown.
Add the kale and salt and continue cooking until the kale and potatoes are tender.
In the meantime, place the onion, soaked cashews, cilantro, chile serrano, lime juice, water, and salt in the blender and process until smooth. Taste and adjust seasoning as necessary.
To make the tacos, heat the corn tortillas, add 2-3 tbsp. of the kale and potato mixture and top with a tsp. of cilantro cream sauce.