Heat oil in a large skillet over medium heat When the skillet and oil are hot, add the onion, potato, and salt. Saute for 5 minutes, stirring occasionally.
Add the jalapeno and spice blend. Stir to coat the potato and onion in spices. Saute for 2 minutes, stirring.
Stir in the plant milk, taking care to scrape up any bits of seasoning stuck to the skillet. Once the mixture reaches a simmer, reduce the heat to low. Cover and simmer until the potato turns soft, 5-10 minutes.
Transfer mixture from the skillet into a high-speed blender. Add the cashews, nutritional yeast, and water to the blender. Blend at medium speed for 20 seconds, then at high speed for 2-3 minutes, until the mixture is heated through and uniformly combined.
If the blending doesn’t heat the queso enough, you can transfer the mixture back to the skillet and warm it over medium-low heat.
Taste a small amount of the queso and add salt as desired. Serve or store immediately.