I've used it on an excellent Middle Eastern surf n turf. Marinade shrimp and lamp chops in it, thinned down with oil if it's too spicy (test beforehand - each one is different). Grill the shrimp and meat, season with salt, pepper and a squeeze of lemon, and serve with a dipping sauce made of more harissa and vinegar or, for a cooler version, harissa and yogurt.
Tunisian, Algerian or Moroccan?
If the latter two, it's a great condiment with grilled sausage, merguez obviously but others as well. Hell, as a condiment on anything grilled, really.
Boiled potatoes tossed with harissa are great. Green beans. In mashed potatoes. Dilute with pasta water and toss with macaroni. Grilled sweet peppers and onions plus harissa make for a -great- quiche.
There's a recipe on this site for harissa-marinated tri-tip.
Here are a bunch if ideas from a previous thread on this topic, sorry I don't know who to credit I just pasted them into a Word document:
Mix it with oil packed tuna and chickpeas or white beans for a fantastic salad.
Mix it with chicken or tuna salad for great sandwiches. Add avocado to the sandwiches if you have it.
Mix it with yogurt and use as a marinade for fish or chicken
Stir into bean and lentil soups or scrambled eggs.
I make a Moroccan style room temperature carrot salad. Simmer slices of carrots in water with a bay leaf, drain and combine with olive oil and harissa while still warm, then refrigerate. Serve at room temperature, garnished with any of the following: chopped mint, chopped cilantro, olives, feta cheese, chopped preserved lemon.
Make yourself a Paris style street sandwich: Grill merguez (Moroccan lamb) sausage. Serve on toasted baguette smeared with harissa.
Marinate chicken pieces in olive oil, cinnamon, salt, cayenne and sugar. Brown pieces, then roast till done. Serve with harissa. (Paraphrased from epicurious.com.)
Tunisian specialty Leblebi (a chickpea stew garnished with hard boiled eggs & tuna). Here's a link - just scroll down a bit http://chef2chef.net/news/club/vol9/r...
I love a little in a bloody Mary, great flavor and a nice change of pace.