Cut the jalapeños into rounds or long strips, depending on your preference.
Infusing the Olive Oil
In a small saucepan, gently heat the olive oil over low heat.
Add the sliced jalapeños (and optional garlic) to the oil.
Allow the mixture to simmer gently for about 5-10 minutes. Be careful not to let the oil smoke; if it starts to smoke, remove it from heat immediately.
Remove the saucepan from heat and allow the oil to cool for a few minutes.
Straining and Storing
Place a fine-mesh strainer or a piece of cheesecloth over a glass bottle or jar.
Using a funnel, carefully pour the oil through the strainer or cheesecloth to remove the jalapeños and any optional added ingredients.