Easy Vegetarian Kofta Curry

Name: Easy Vegetarian Kofta Curry
Ingredients: 1 tablespoon olive oil; 1 tablespoon butter; 1 teaspoon cumin seeds; 3 green cardamom pods; 2 whole cloves; 1 cinnamon stick; 1 bay leaf; 0.5 onion, grated; 1 (2 inch) piece ginger root, peeled and grated; 1 clove garlic, crushed; 1 (14.5 ounce) can diced tomatoes; 1 teaspoon ground coriander; 0.5 teaspoon ground turmeric; 0.5 teaspoon ground cumin; 0.5 teaspoon garam masala; 0.5 teaspoon cayenne pepper; 0.5 teaspoon salt, or to taste; 0.25 cup whole milk yogurt; 24 frozen meatless vegetable meatballs (such as IKEA®'s frozen vegetable balls); 0.25 cup hot water, or as needed