Harissa often contains seeds like coriander, caraway, or cumin, and usually olive oil. It may also contain tomatoes. It is used both as a condiment and as an ingredient in recipes.

In Tunisia, harissa is served at virtually every meal as part of an appetizer. It is used as an ingredient in a meat (goat or lamb) or fish stew with vegetables, and as a flavoring for couscous. It is also used for lablabi, a popular chickpea soup usually eaten for breakfast.

Lemon juice is sometimes added. In Saharan regions, harissa can have a smoky flavor.