Heat up 1 cup agave syrup and 1/4 cup water in a small saucepan. Add the serrano peppers and let simmer for approximately 10 minutes. Turn off the heat and let the syrup cool to room temperature. Use a strainer to pour into your syrup container.
Add the above ingredients into a glass and give it a swirl. Chili lime salt, or Tajin are a great way to add a little flare to the rim.