NABEUL, Tunisia — For years, Tunisians have been picking bright red peppers, combining them with garlic, vinegar and spices and turning them into a saucy spread called harissa. The condiment is a national staple, found in homes, restaurants and food stalls throughout the coastal North African nation. Brick-red, spicy and tangy, it can be scooped up on bread drizzled with olive oil or dabbed onto plates of eggs, fish, stews or sandwiches. Harissa can be sprinkled atop merguez sausages, smeared on savory pastries called brik or sandwiches called fricassées. In Nabeul, the largest city in Tunisia’s harissa-producing Cap Bon region