Slow Cooker Chicken Korma

Name: Slow Cooker Chicken Korma
Ingredients: 4 chicken breasts , cut into 1 inch cubes; 1 white onion , quartered; 3 cloves garlic , minced; 1 tablespoon ginger , grated; 13.5 ounces light coconut milk; 4 ounces red curry paste; 1/2 teaspoon kosher salt; 1/2 teaspoon ground black pepper; 1 cup frozen peas; 15 ounces canned chickpeas , rinsed and drained; 3 tablespoons fresh cilantro , roughly chopped; 10 ounces plain Greek yogurt; 2 tablespoons corn starch; Scallions and lemons for garnish; 4 cups ginger rice