Prepare The Brine: To a large pot, add the water, salt, peppercorns, garlic, bay leaf, lemon zest, and sliced lemon. Heat the mixture gently over medium-low heat on the stove, stirring until the salt is fully dissolved, which should take about 5-7 minutes, do not boil the brine. Once dissolved, let the brine cool to room temperature. Or, you can add 1/2 cup of ice cubes to speed up the process. However, reduce the initial amount of water by 1/2 cup to maintain the brine’s strength.
Brine Turkey: Place the turkey breast in a large container or brining bag. Then, pour the brine over the turkey, ensuring it's fully submerged in the brine. Cover and refrigerate overnight (8-12 hours) or at least 6-8 hours for a quicker brine.
Prepare The Turkey For Roasting: Once done brining, rinse the turkey breast under cold water to remove excess salt. Then, pat it dry with paper towels.
Prepare The Herb Rub: Combine the butter with the rosemary, thyme, sage, pepper, and pinch of salt. After that, rub the turkey breast generously with the herb mix, including on top of the skin and under the skin for maximum flavor.
Roasting Pan: Layer thick slices of onion along with fresh herbs and garlic cloves at the bottom of the roasting pan or beneath the roasting rack. The onion slices can elevate the turkey slightly, for even cooking, or you can place the turkey breast directly on a roasting rack. Next, add one cup of low-sodium chicken broth or water to the pan to keep the turkey moist and flavorful as it roasts.
Roast the Turkey: Roast the turkey uncovered at 325°F. For a bone-in turkey breast, roast it for about 20-25 minutes per pound (about 1.5 hours for a 3.5-pound turkey breast, or until the internal temperature reaches 165°F in the thickest part of the turkey breast). Or, for boneless turkey breast, about 18 minutes per pound (about 1 hour to 1 hour and 15 minutes for a 3-pound turkey breast, or until the internal temperature reaches 165°F).
Let It Rest: After roasting, it's important to let the turkey rest for 15-20 minutes. This allows the juices to redistribute throughout the meat, ensuring it remains tender and juicy when sliced. If you slice the turkey immediately, the juices will escape, resulting in drier meat. Letting it rest also gives the turkey time to finish cooking from residual heat, ensuring it's perfectly done. After resting, slice against the grain to ensure the meat is as tender as possible.