Make the sauerkraut

1. Drain the sauerkraut really well. It can help to press down into the colander to get as much moisture out.
2. To a non-stick pan over medium heat, add the sauerkraut, brown sugar, and caraway seed. Stir to combine and cook for about 5-10 minutes or until the brown sugar melts and the sauerkraut has a little bit of brownness to it.

Assemble and Bake

1. On a lightly floured board or counter, roll/pat the pizza dough into an 18×12″ rectangle.
2. Using a pizza cutter or sharp knife, cut the dough into quarters.
3. Cut the kielbasa string into 4 equal-size segments. Cut a slit into each kielbasa lengthwise but do not cut all the way through. In each slit add 1 whole string cheese or, if halved lengthwise, add half to the slit.
4. Once the sauerkraut is cooled, add about 2-3 Tablespoons of it to the middle of the pizza dough squares.
5. On top of the kraut, add about a teaspoon or two of whole grain and dijon mustard mixture. *You can use both mustards or either one. I like the taste of both combined.
6. Next, add the cheese-stuffed kielbasa on top. Pull up the long edges, pinching to close. Grab the end pieces and pull up and over, pinching to close.
7. Place on a parchment-lined baking pan. Lightly spray with cooking spray and cover to proof for 30 minutes while the oven heats up.
8. Preheat the oven to 400F, and the rack in the middle. Line a rimmed baking sheet with parchment. Set aside. Right before baking, brush the bombs with an egg wash and sprinkle with poppy seeds. Bake for ~18-22 minutes or until the bombs are golden brown.
9. Remove from the oven and immediately transfer to a cooling rack.