Place cauliflower, onion, lentils, water, cashews, garlic, and miso in the Instant Pot. Stir to combine. The water should not completely cover the other ingredients.
Use the manual setting and cook for 6 minutes, then release the pressure.
Add the mustard and apple cider vinegar to the pot and stir. Allow to cool a few minutes
Bring a large pot of water to a boil. Salt the water and add the pasta. While you complete the sauce, cook the pasta until al dente, then drain. Return the pasta to the pot.
Preheat the over to 350 degrees F.
Carefully place the sauce ingredients in a blender jar. If you have a large jar, this amount of sauce should fit.
Blend the sauce until it is very smooth. Adjust seasonings.
In the pasta pot, add enough sauce to thoroughly coat the pasta. Some of the sauce will be absorbed during baking, so be generous. I used about 2/3 of the sauce for 1lb of pasta.
Pour the saucy pasta into a baking dish. Sprinkle with nutritional yeast. Bake for 15-20 minutes, until the top dries out a bit.
Remove from the oven. Sprinkle with paprika and serve.