Step 1

Heat the olive oil in a small skillet over medium heat. Toss the bread cubes in the oil, turning with tongs or a heat-proof spatula to toast on all sides, about 4 minutes. Season with salt and pepper. Transfer to a plate to cool. (You can make these up to one day in advance; just be sure to cool completely and store in an airtight container.)

Step 2

Pull the chive blossoms from the chives and chop the green shoots.

Step 3

Heat the stock in a large soup pot over high heat until simmering. Add the peas and cook until bright green and just cooked, 8 to 10 minutes. Remove from the heat and use an immersion blender or transfer the soup to a blender in batches to process until smooth, about 3 minutes. Add the wasabi (if using) and season with salt and pepper. Add the yogurt and process until smooth and slightly creamy, 2 to 3 minutes. Return to the pot and keep warm over a low flame until you are ready to serve.

Step 4

Ladle the soup into bowls, top with croutons, and drizzle with olive oil. Season with pepper and scatter the chopped chives and their blossoms generously over the top. Serve warm.