Rinse and peel the asparagus up to two-thirds of the way down, then snap them in half at that point. Next , slice the peeled section into rounds.
Cook the sliced asparagus stalks, onion, and potato with a knob of butter in a skillet or Dutch oven for 15 minutes over medium heat, covered.
Stir occasionally. The vegetables should not brown.
Prepare the broth according to the manufacturer's instructions (dissolve the bouillon cube or steep the tea bag). Add it to the vegetables, along with the specified amount of boiling water, and let it simmer, covered, for 15 minutes.
Once the cooking is done, blend the mixture thoroughly using an immersion blender or, better yet, a stand blender, to achieve a perfectly smooth texture and avoid any stringy bits.
Return to the heat, add the crème fraîche, and stir a few times to warm it through.
Meanwhile, slice the asparagus tips in half lengthwise and sauté them for two minutes in a little olive oil. Season with salt and pepper.
Pour the soup into bowls or plates, and top each one with the roasted asparagus tips while they’re still warm. Serve immediately and enjoy!