A mortar and pestle is the traditional way to grind spice blends into pastes and powders. It is time consuming, but extracts more of the natural oils and flavors from the spice blend. An electric blender can be a short cut. If you have the time, use the mortar and pestle. They are made from many different materials; lava stone, ceramic, marble, wood. I prefer a ceramic mortar with a long-handled pestle to give me more leverage while grinding.