Place the almonds in a bowl and cover them with approximately 3/4 cup of water. Cover the bowl and let it soak overnight or for about 12 hours. Drain and rinse the nuts prior to using. *NOTE this first step is optional but the nuts will be softer and much easier to blend into a creamy texture.
Place the drained nuts into a high-speed blender, and add an additional 1/2 cup of cold water, the lemon juice, olive oil and garlic powder. Blend until smooth.
Add the salt and harissa paste to taste. If the mixture is too thick, or grainy, add additional water. Blend again to combine everything.
This can be used immediately but tastes even better the next day when the flavors have a chance to blend. Store it in a covered bowl for up to a week, and if any water seeps out at the bottom, just drain it off.