Place each round steak between 2 pieces of plastic wrap and use a meat mallet to pound the round steaks to ¼" thickness.
Season the steaks with 1 teaspoon salt, ½ teaspoon black pepper, and garlic powder. Set aside while preparing the filling.
In a large oven-proof skillet over medium/high heat, cook the bacon until almost crisp.
Drain off some of the fat, and reduce the heat under the pan to medium. Add almost all of the diced carrots and celery to the pan (see note below) along with all of the onion in with the bacon in the skillet. Cook, stirring occasionally, until the vegetables have softened slightly (about 5 minutes). *Note - do not add the reserved ½ cup carrots and ¼ cup celery specified earlier for the sauce. Those are added later.
Add the pickles and dill weed to the skillet along with the remaining ½ teaspoon salt and ½ teaspoon pepper. Cook and additional 1-2 minutes, stirring occasionally.Turn off the heat under the skillet while preparing the beef rolls, and remove the vegetable and bacon filling to a bowl until it's cool enough to handle.
Place approximately 1 tablespoon of filling onto one end of each pounded and prepared round steak piece.Roll each flattened beef round steak over and around the cooked filling, making sure to incase the filling well with the beef using kitchen twine or toothpicks to securely close.
Meanwhile preheat oven to 325 °F (165 ℃).
Heat the skillet again to medium/high on the stovetop and the add olive oil.Brown the secured beef rolls on all sides in the skillet. Once browned on all sides, remove them to a plate and keep them warm while preparing the sauce.
Reduce the skillet heat to medium/low. Carefully add the Merlot wine and use a slotted spatula to deglaze the skillet by gently scraping up the browned bits of beef that have stuck to the bottom of the skillet during the browning of the beef rolls.
Stir the tomato paste into the skillet, and cook for 2 minutes.Carefully pour in the beef broth plus any remaining carrot, onion, and bacon filling you may have leftover from filling the rolls, along with the reserved ½ cup of diced carrots, and ¼ cup of diced celery from before.
Nestle the browned beef rouladen back into the pan with the sauce.Cover the oven-proof skillet and cook in the preheated oven for 2 hours.
Once fully cooked, use a slotted spoon or spatula to remove the beef rouladen to a plate, cover, and keep warm. Return the skillet to the stovetop.Stir the cornstarch into 1 cup of water (making a slurry) and pour it into the skillet along with the sauce in the pan.Cook, stirring occasionally over medium heat until the sauce thickens (approximately 2-3 minutes).
To serve, spoon the thickened sauce over the beef rouladen and garnish with additional dill, if desired.Serve the German beef rouladen over mashed potatoes, spaetzle, or even rice (not shown).
Notes
Store any leftovers in an airtight container in the refrigerator for up to 5 days.May be frozen after cooking. Cool completely. Freeze in an airtight freezer container or freezer bag for up to 3 months. Label and Date. Thaw in the refrigerator overnight.