While your pot is coming to room temperature, trim the asparagus and cut into 1-inch pieces, dice the zucchini into 1/2-inch cubes, finely chop the shallots and mince the garlic. Place the raw cashews in a bowl and pour hot water over them—let them soak for at least 5 minutes while you prep everything else. This softens them for blending into a creamy base. Finely chop the fresh chives and set aside for garnish.

Heat a large pot over medium heat and add the diced shallots with a pinch of salt—this helps them release moisture and soften faster. Cook for about 2-3 minutes, stirring occasionally, until they become translucent and fragrant. Add the minced garlic and cook for another minute until it becomes fragrant but doesn't brown. I like to keep the heat at medium rather than high here because it coaxes out the sweet, mellow flavors of the aromatics rather than creating harsh, burnt notes.

Add the fresh thyme sprigs, onion powder, and nutritional yeast (or all-purpose seasoning) to the softened aromatics. Stir well and toast these seasonings for about 30 seconds, allowing them to bloom and develop deeper flavor. This blooming step is crucial—it activates the flavors and prevents them from tasting dusty or flat in the finished soup.

Add the asparagus and zucchini pieces directly to the pot and stir to coat them with the seasoned aromatics. Cook for 1-2 minutes, just until they begin to soften slightly and release their natural moisture. Pour in the vegetable broth and drain the soaked cashews (discarding the soaking water), then add them to the pot as well. Bring everything to a gentle boil, then immediately reduce heat to low, cover the pot, and simmer for 5-8 minutes until the vegetables are very tender and easily pierced with a fork.

Remove the pot from heat and let it cool for 1-2 minutes so the steam subsides slightly. Carefully transfer the soup to a blender in batches (or use an immersion blender directly in the pot) and blend until completely smooth and silky. I find an immersion blender is faster here and creates less cleanup—just make sure to blend thoroughly for at least 1-2 minutes to achieve that luxurious, creamy texture without any grittiness.

Return the blended soup to the pot if needed and stir in the fresh lemon juice and red pepper flakes for brightness and subtle heat. Taste the soup carefully and season with salt and black pepper to your preference—start with a small amount and add gradually, tasting as you go. Gently warm the soup over medium-low heat if it has cooled during blending, but don't let it boil.

Ladle the soup into bowls and top each serving with a small dollop of yogurt swirled gently into the surface, and a sprinkle of the fresh chives. The cool yogurt creates a beautiful contrast against the warm, creamy soup, and the chives add a fresh onion note that brightens the dish.