Place the cashews in a blender and cover with hot water. Allow to sit for at least 5 minutes. Drain the cashews and return to blender. Add lemon juice, olive oil, garlic powder, nutritional yeast, cayenne pepper, Dijon mustard, salt, pepper, and ¾ cup water.
Blend until smooth. Set aside.
Black Bean Dip
Preheat the oven to 475 degrees Fahrenheit. In a 10-inch cast iron or oven-proof skillet, heat the 3 tablespoons of olive oil over medium heat. Add the onions, stirring occasionally, until softened. Add the jalapeños and garlic and cook for one minute.
Stir in the tomato paste, black beans, cumin, paprika, cayenne (if using), and ½ cup hot water. Add a couple healthy pinches salt and pepper, or more to taste. Pour the cashew cheese sauce over the bean mixture and stir gently to incorporate.
Place skillet in the oven and bake for 5-8 minutes. The top of the dip should start to turn golden. Serve immediately with chips or tortillas and hot sauce, if desired.