Combine rosemary, parsley, bay leaf, thyme, peppercorns, and lemon peel in a cheesecloth bundle and tie closed with kitchen twine. Put the turkey breast in a medium Dutch oven and cover with enough room temperature broth to completely cover meat (about 6 – 6 ½ cups depending on the pot.) Add herb bundle and bring to a gentle simmer over medium-low heat, then reduce to a bare simmer (do not let it boil!) and cook 30-45 minutes or until meat reaches 155°. Transfer meat to a bowl and cover with plastic wrap, punching a few holes in the wrap to allow steam to escape. When cool enough to handle, trim out the strip of cartilage running through the thickest part, slice across the grain into ½” slices, chop into small pieces, cover and set aside.

While meat poaches heat a medium sauté pan over medium heat, add butter then the onion, celery, and carrots and cook until almost soft, about 10 minutes. Whisk in the 1/3 c. flour and cook, stirring constantly, until vegetables are completely coated and bubbly. Remove herb sachet from stock, whisk vegetable mixture and milk into stock and return to a simmer over medium-low heat, stirring occasionally. Add chopped meat then adjust liquid level if necessary by adding more chicken broth. (You should have a medium-thick gravy with lots of room for the meat to float in, as the dumplings will absorb some of the liquid as they cook.) For a thicker broth make a slurry by adding 1 Tbsp. flour to a few tablespoons of cool broth and whisk into the hot mixture. Add lemon juice, salt, and pepper to taste and bring to a very gentle simmer.

Prepare dough for dumplings; drop by tablespoonfuls onto barely simmering mixture. Cook uncovered 10 minutes, cover and cook 15 minutes longer.