Bring water to boil. Add carrot, onion and cashews and boil for about 30 minutes on low-medium heat.
After the boiled vegetables cool down, drain them but save 1/3 of a cup of water for blending.
Add this mixture to a blender along with milk, nutritional yeast, lemon juice, black salt, mustard, turmeric, garlic, black pepper and salt. Blend together into a creamy, smooth texture.
Adjust salt/lemon to taste, then refrigerate.
Heat up the portion needed per use.
Notes
Note: This cheese sauce will stay fresh for up to two weeks.