Place the cauliflower and cashews in a pot with enough water to cover them plus two inches. Place the pot over medium-high heat and bring to a boil. Reduce the heat to medium low and let simmer for about 15 minutes, or until the cauliflower is fork tender.
Drain the cauliflower and cashews, saving the cooking water. Allow to cool slightly.
Place the cauliflower, cashews, ⅓ cup of the reserved cooking water, lemon juice, apple cider vinegar, onion powder, garlic powder, and sea salt in a blender and blend until smooth and creamy. If the mixture is too thick, add a little more of the reserved cooking water, a tablespoon at a time, until it reached the desired consistency.
Transfer the mixture to a small bowl and mix in the sesame seeds, poppy seeds, minced garlic, and minced onion.
Refrigerate until ready to use.