Make Pickled Vegetables:
Thinly slice the red onion and radish. Use your hands to make sure all the pieces are separated and add them to a glass jar.
In a pan, add the vinegar, salt, water, sugar and peppercorns. Heat until sugar is dissolved. Pour mixture over the red onions and radishes and make sure they are fully saturated. If you need more, add equal parts vinegar and hot water until the onion pieces are fully submerged. Seal the jar, give it a shake and let it sit on the counter for 1 hour. Then move it to the fridge. Within 4 hours the onions should be bright pink and ready to go!
Spread skyr on top of toasted bread slice and top with pickled herring, pickled vegetables, and garish with fresh herbs of choice.