Combine sugar and water in a small saucepan over medium heat.
Add jalapeño slices (with or without seeds, depending on desired heat level).
Bring to a simmer, stirring occasionally until the sugar is completely dissolved about 3-5 minutes.
Remove from heat and let cool completely with jalapeño slices still in the syrup. The longer the jalapeño steeps, the spicier the syrup will be.
Strain through a fine-mesh sieve into a clean container and refrigerate until ready to use. (Can be made up to 2 weeks in advance.)
Notes
1. Nutritional information is only an estimate. The accuracy of the nutritional information for any recipe on this site is not guaranteed. The nutritional value will vary based on the brand of ingredients used and how much the simple syrup is used. It does not include the nutritional value of how the simple syrup is used. It does not include the nutrition for any substitutions. 2. Be sure to check out the Key Ingredients along with the Recipe Tips and Notes sections found in the post, for more tips, options, substitutions, and variations for this recipe! You will also find step-by-step photos there.