Preheat the oven to 350 degrees F.
Place turkey breast in a roasting pan and pat dry with a paper towel. Tip: if you don't have a roasting pan, roll up some aluminum foil into a few rolls and place them on the bottom of a baking pan for the turkey breast to sit on. This will prevent the bottom from getting soggy and help cook it evenly.
In a medium bowl, mix together the mayonnaise, garlic, lemon zest, herbs, sea salt, and pepper.
Slather the mayonnaise mixture all over the outside of the turkey breast, and under the skin if possible.
Roast the turkey in the preheated oven for ~90 minutes, or until meat thermometer reads 165 degrees F.
Remove from the oven. Transfer 3-4 tablespoons of the drippings to a medium saucepan.
Cover the turkey breast with foil to keep warm.
Add the flour and broth to a mason jar and shake until well combined and no lumps remain.
Heat the drippings along with 1 teaspoon of butter over medium heat.
Slowly add the flour/broth mixture, whisking continuously, until smooth.
Simmer for a few minutes until it has thickened.
Season with salt and pepper, to taste.
Serve the turkey breast sliced with gravy. Enjoy!