Chickpea, Cucumber, Tomato and Avocado Salad

INGREDIENTS

• Zest and freshly squeezed juice from 1 large lemon (about 2 teaspoons zest and 1/4 cup juice)
• 1 tablespoon extra-virgin olive oil
• 1 teaspoon ground cumin, or to taste
• 1/2 teaspoon salt
• 1/4 teaspoon sugar
• Freshly ground black pepper
• 1 cup cooked chickpeas (if using canned chickpeas, rinse and drain them)
• 8 ounces small seedless (English) cucumbers, cut into 1/2-inch pieces (2 cups)
• 8 ounces tomato, peeled and seeded if desired, cut into 1/2-inch dice (1 cup)
• 3 or 4 scallions or spring onions, white and light-green parts, finely chopped (1/3 cup)
• 1/3 cup loosely packed, finely chopped flat-leaf parsley (about 12 stems)
• Flesh of 1 ripe avocado (9 to 10 ounces), cut into 1/2-inch dice