Hard boil 7-9 large eggs for 12 minutes, then place in an ice bath.
Make the beet brine by combining the water, apple cider vinegar, diced beet, 1 teaspoon salt, and 1-2 teaspoons maple syrup in a saucepan. Bring to a boil, then reduce heat and simmer for 10 minutes.
Strain the brine and allow it to cool to room temperature before pouring it over the hard-boiled eggs. Refrigerate the eggs in the brine for 15 hours to achieve the desired color.
Make the egg filling by mashing the 6-8 hard-boiled egg yolks with 1 teaspoon Dijon mustard, ½ teaspoon apple cider vinegar, 4-5 tablespoons mayonnaise, ¼ teaspoon salt, and ¼ teaspoon black pepper.
Garnish the deviled eggs with fresh dill and chives.
