Baked Quinoa Falafel Pita with Tzatziki

Name: Baked Quinoa Falafel Pita with Tzatziki
Ingredients: ½ Cup water; ¼ Cup quinoa, uncooked; 1 (14.5-ounce) can chickpeas, drained, rinsed, and patted dry; ¼ Cup chopped red onion; 2 cloves garlic; ½ Cup flat-leaf parsley, chopped; ½ Teaspoon fine sea salt; ¼ Teaspoon ground black pepper; ½ Tablespoon cumin; ½ Tablespoon dried coriander; 1¼ Teaspoon chili powder; 1/8 Teaspoon cayenne pepper; 1 egg yolk; ¼ Cup olive oil, divided; ½ cucumber, peeled and grated; 2 cloves garlic, minced; Juice of 1/4 small lemon; 2 Tablespoons olive oil; 1 Cup 2% plain Greek yogurt; 1 Teaspoon dried dill; ¼ Teaspoon kosher salt; 2 whole wheat pitas, cut in half