Most grocery stores carry harissa spice these days. You can find it in the spice section or the international foods section. Harissa is typically made in a spice blend or a paste. However, if you’re not in luck finding it in your local grocery store, you can order online or check your local ethnic market. If you are feeling adventurous, you can make your own.  The benefit of making your own is that you can adjust the flavor and heat level to your liking.