Slice the mushrooms very thinly.

Then slice the vegetables and the egg to your liking.

Next, mix together the olive oil and lemon juice with the remaining ingredients.

Season with salt and pepper (and if you are using them, stir in the mustard and honey as well).

After that, mix together the mushrooms, egg, corn, and vegetables with the dressing.

Finally, sprinkle with freshly chopped parsley.

Let it sit for 5 to 10 minutes so the mushrooms soften slightly and the flavors come together.