Combine the flour, salt, water, oil and vinegar in a stand mixer fitted with the paddle attachment. You will get a soft dough. Make sure it is not too dry, add more water if necessary. Mix until the dough forms a ball, it will not be smooth at this point.
Switch to the dough hook and knead the dough for 5-8 minutes or until the dough is very smooth. It may not come together in one ball, but will be a few balls chasing each other around the bowl. Once it is smooth take it out, cover in plastic wrap and allow to rest for at least 30-90 minutes. I let mine sit overnight in the refrigerator.
When ready to roll out your dough and make the strudel, preheat the oven to 400°F. Mix together the cherries (or raisins) and rum in a small bowl and set aside. Mix together the cinnamon and sugar in another small bowl and set aside.
In a large skillet, heat 3 tablespoons of the butter over medium heat. Add the breadcrumbs and cook whilst stirring until golden brown and toasted. This will take about 3 minutes.
Once your dough has rested you will need to set up a large work area with a cloth. Dust the cloth generously with flour and rub the flour into the cloth. This prevents the dough from sticking as you work it. I started the process by using my largest rolling pin. Once the dough has gotten too big and too thin to use the pin you will just use your hands to finish the dough. This is where you begin to listen to the dough. Turn up that music, get another cup of tea or a glass of wine and relax!
Only use the backs of your hands and be sure to remove all of your jewelry. You will also want to wear short sleeves, because you get your arms in on the action too. Start at the short end and very gently slide your hands under the dough. Starting in the center slowly move your hands out to the edges of the dough, pulling very gently on the dough. Repeat this move over and over, moving in towards the center. Then move to the other side and repeat on that end. Do this until you have stretched every part of the dough evenly. Don't worry about it being paper thin at this point! You just want to stretch it evenly.
Now you want to stretch it by holding one side down with your hand and forearm and gently stretching by pulling from underneath the dough with the other hand. You need to move slowly so that you can feel if the dough is getting so thin it might tear. If there are spots that feel thin, lighten up with your pressure. If there are sections that get very thin, just leave them be and focus on the parts that are thicker. Remember that you are going to roll this up and even if you get several tears in your dough NO ONE WILL EVER KNOW!
Repeat both stretching techniques until the dough measures 3'x2' and is paper thin, or close to that.
Using your hands gently rub the melted butter onto the entire surface of your dough. There are special pastry brushes made of feathers that are soft enough for the job, but don't try this with a regular hair or rubber bristle brush or you will tear the dough.
Sprinkle the toasted bread crumbs over the entire surface of the dough. Spread the nuts about 3 inches from the short end of the dough in a 6-inch wide strip. Mix the apples with the cherries (or raisins), including the rum, and the cinnamon sugar. Spread the apples over the nuts. Using the cloth to help you, roll the dough into a tight log.
Curve the strudel into a horseshoe shape to fit on the sheet pan, lined with parchment or a silpat. Tuck the ends under and coat with the remaining butter.
Bake in the top 1/3 of oven for 30 minutes or until deep golden brown. Allow to cool for at least 30 minutes and cut with a sharp serrated knife. The recipe says to eat the same day, but we all loved the left overs for breakfast the next day! Serve with softly whipped cream and a good cup of coffee!