If you like hot food, you should keep some harissa in the fridge. I stir it into couscous and its accompanying sauce, of course; and also into pasta sauces, hummus, and soups. Here is a recipe; I also buy the stuff in tins and tubes. In both cases, I decant the harissa into a glass jar, and cover it with olive oil. If the harissa stays submerged, it should last for a month.
For lunch yesterday, I fried a chopped onion and half a clove of chopped garlic in some olive oil, starting on a medium heat and then turning it down as the vegetables threatened to catch. I sliced six button mushrooms and threw them into the pan, grinding over some salt and pepper and turning up the heat again. I stirred constantly, in order to avoid burning the onions. The mushrooms disgorge water; you can turn the heat right up when they do, to evaporate it. The total frying time was about 10 minutes. I turned off the heat, and stirred in a teaspoon of harissa.
I toasted two slices of bread, spread hummous on them, and tipped the mushroom mixture on top.