Rinse the wild rice under cold water in a fine-mesh sieve until the water runs clear. Set aside.
Heat the avocado oil in a large pot or Dutch oven over medium heat. Add the chopped onion, sliced carrots, and sliced celery. Cook, stirring occasionally, until the vegetables are softened, about 8-10 minutes.
Add the minced garlic and crumbled dried rosemary to the pot. Stir constantly for about 1 minute until fragrant.
Pour in the water and add the rinsed wild rice and a teaspoon of salt. Bring the mixture to a boil, then reduce the heat to low, cover, and simmer for 45-55 minutes, or until the wild rice is tender and has popped open.
While the rice simmers, prepare the cashew cream: combine the soaked and drained cashews with 1 cup of fresh water in a high-speed blender. Blend until completely smooth and creamy, about 2-3 minutes.
Once the wild rice is tender, stir in the cashew cream and a pinch more salt to taste. Cook, stirring gently, for another 5 minutes to heat through and thicken the soup slightly. Adjust salt as needed. Serve hot.