First chop up the asparagus (reserve about half of the tips), onion, garlic and potato (peel and wash it first). Prep work: check.
In a medium pot heat the olive oil and butter over medium heat. Cook the onion until just softened (2-3 minutes). Add in the garlic, asparagus and potato. Cook until the asparagus begins to turn bright green (3-4 minutes). Season with a little salt and pepper and then pour in the broth. Allow to simmer for 20 minutes or until the potatoes can be easily sliced through with a knife. Now use your immersion blender to blend everything up. Or you can work in batches and puree in a blender (but be careful when transferring hot liquids).
In a small pot filled with 2-3 cups water blanch the reserved asparagus heads until bright green and cooked through but still crunchy. Drain and reserve. To serve garnish with a big dollop of greek yogurt and a few of the cooked asparagus heads.I highly recommend squeezing a little lemon juice over the top of the soup just before eating. I love how citrus can add just a little pop of flavor to veggies, salads and lots of soups. Yum!