This Mediterranean dish features harissa -- a blend of chile paste and spices; chopped dried chiles can be used instead.
Place chickpeas in a large bowl and cover with 2 cups water. Let stand overnight in the refrigerator.
Drain chickpeas. In a stockpot, heat olive oil over medium heat. Add onion and garlic; cook, stirring occasionally, until translucent, 5 minutes. Add chickpeas and 5 cups of water. Cover; bring to a boil. Reduce heat; simmer until chickpeas begin to soften, about 30 minutes.
Add 1 teaspoon cumin and 1 teaspoon harissa. Cover and simmer until chickpeas are tender, about 45 minutes. Add salt.
Let stand about 1 hour to cool. Transfer half the soup to a blender; blend to a coarse pur? Repeat with remaining soup. Return to stockpot and reheat.
Place capers, turnips, eggs, tuna, remaining harissa, scallions, and lemon in a relish tray or in individual bowls. Serve soup with the assorted condiments.