It's easy to make an authentic harissa powder at home by grinding whole toasted peppers and spices into a powder. But, if you don't have a spice grinder or the required ingredients, this harissa powder substitute made from ground spices will deliver all the harissa spice flavours you need.
Mix the ground spices in a small bowl and transfer the spice blend to an airtight container. Store in a cool, dark spot for up to 6 months.
Notes
Add more cayenne pepper for a spicier harissa powder, or swap for a milder chilli like Aleppo pepper, gochugaru or Kashmiri for less spicy harissa seasoning. Omit the chilli powder for a non-spicy alternative for harissa spice.
You can also add ground caraway for an even more authentic flavour if you have any, but it is not widely available in grocery stores.