Set a pot of water on the stove and bring to almost boiling. More like an active and very heated simmer.
Add your vinegar, let simmer. It should not be boiling, just hot
Toast muffin (I use the oven so need more time than most)
Crack an egg into a bowl. If the yolk breaks you will have to do it again. So use some finesse. Also, this bowl should be small-ish. like a cereal bowl
Swirl the water in a circular motion. Get it moving and then...
Now take your bowl and lower it to just above the water, slightly tilted. Now put the egg into the water with ease.
Allow it to cook for about 5 minutes depending on how you like your yolks. After 2-3 minutes you'll be able to take a spatula or similar and find the egg in the murky water and lift lightly to the top so you can view the yolk.
If your tool is a flat with holes that's best as it strains out all extra water when you're lifting it from the water onto your bread. I often use a spatula and try to train it at an angle because I use the spatula for almost everything.