Begin by cutting the cucumber into thin strips using a peeler or mandoline. To make this easier, start by slicing a few strips from one side, then rotate the cucumber and repeat on the other sides until you’ve created a manageable, cube-like shape. This method ensures the surface area remains small enough for the peeler or mandoline to handle easily.

Place the cucumber strips in a bowl and sprinkle them with salt. Gently massage the salt into the cucumbers with your hands, ensuring they are evenly coated. Next, place a plate over the cucumbers and weigh it down with something heavy (like a can or a small pot). Let it sit for at least 15 minutes. This process draws out excess water from the cucumbers, preventing them from releasing moisture later and making the salad watery. After 15 minutes, drain off the water that has accumulated, and gently squeeze the cucumber strips to remove any remaining excess water.

In the meantime, prepare the yogurt sauce. In a mixing bowl, combine mustard, balsamic vinegar, and a pinch of salt, stirring until the salt dissolves. Whisk in the olive oil until the mixture emulsifies, then add the soy yogurt. Stir until you have a smooth, creamy sauce.

Add the drained cucumber strips to the sauce, tossing them gently to ensure they’re evenly coated. Finish by mixing in some freshly chopped parsley. Serve the salad immediately, or refrigerate it for a short time to allow the flavors to meld.