Vegan Spring Tortilla Soup With Avocado

1 tablespoon avocado oil
1 tablespoon cumin seeds
2 medium garlic cloves, pressed
2 tablespoon canned chipotle chilies, finely chopped
1½ cups leeks, halved and slivered
3 teaspoons salt, divided
1 cup zucchini, cut into ¼-inch dice
1 cup corn kernels
2 cups fresh or canned chopped tomatoes
1 tablespoon tomato purée
3 cups water
¾ cup cilantro, divided, finely chopped
½ teaspoon black pepper
1 tablespoon lime juice
¼ avocado, cut into ¼-inch dice
2 5-inch corn tortillas, divided in eighths