Step 1: Prepare your vegetables. Trim the woody ends off the asparagus and cut the tender parts into 1-inch pieces. Chop the onion and mince the garlic. If using fresh peas, shell them.
Step 2: In a large pot or Dutch oven, melt the butter over medium heat. Add the chopped onion and cook until softened and translucent, about 5-7 minutes.
Step 3: Add the minced garlic and cook for another minute until fragrant, being careful not to burn it.
Step 4: Stir in the vegetable broth and bring to a simmer. Add the asparagus pieces and cook for 5-7 minutes, or until tender-crisp.
Step 5: Add the green peas and spinach. Cook for just 2-3 minutes more, or until the peas are tender and the spinach has wilted. Stir in the heavy cream and lemon juice. Season generously with salt and freshly ground black pepper.
Step 6: Carefully transfer the soup in batches to a blender (or use an immersion blender directly in the pot). Blend until smooth and creamy. If you prefer a chunkier texture, blend only half of the soup and stir it back into the pot with the unblended portion.
Step 7: Return the blended soup to the pot, if necessary, and reheat gently over low heat, ensuring it doesn’t boil. Taste and adjust seasonings as needed.
Step 8: Ladle the hot soup into bowls. Garnish with a swirl of cream, a sprinkle of fresh dill or chives, and a grind of black pepper. Serve immediately.