Boil water: Heat 1 cup of filtered water to about 80°C (175°F), not boiling.
Mix dry ingredients: In a mug, stir together cinnamon, ginger, and turmeric if using.
Pour in hot water: Add the hot (not boiling) water and whisk to combine.
Cool slightly: Let the mixture cool for 3–5 minutes.
Add ACV and lemon: Stir in the apple cider vinegar and lemon juice.
Sweeten if needed: Add honey if desired, and mix well.
Serve: Enjoy warm or at room temperature. Stir again before sipping as spices may settle.