In a medium skillet, bring the water to a boil and add the chopped carrot and potato. Cook for about 10-15 minutes, or until the vegetables are soft and easily pierced with a fork. Drain and set aside.
In a high-speed blender, combine the soaked and drained sunflower seeds, boiled potato and carrots, sunflower seeds, and all remaining ingredients except the milk. Add ¾ cup of milk to start.
Blend on high until the mixture is completely smooth and creamy. If the sauce is too thick, add more almond milk, a little at a time, until you reach your desired consistency.
Pour the blended cheese sauce into a skillet and heat over medium-low, stirring constantly until warm and slightly thickened. Taste and adjust seasoning if needed. This will take a few minutes.
Serve the vegan nacho cheese sauce warm over nachos, drizzled on tacos, or as a dip with your favorite snacks.