In a large bowl, whisk together the lemon juice (starting with 2 tbsp), maple syrup, dijon, salt, and lemon zest (if using). Add the chickpeas, tomatoes, avocado, olives, spinach, and basil (and chives, if using). Toss through, gently so not to break up the avocado too much. Taste, and if you'd like more lemony tang, add the extra 1/2 tbsp of juice. Season as desired with more salt or with some pepper. Serve!