Combine the herbs and oil in a heat-safe jar, adding a little extra oil if needed to make sure the herbs stay covered.
Place the jar of oil/herbs down into a small saucepan containing a few inches of water. (Enough water to cover a good portion of the jar sides, but not too much so it starts to float.)
Heat the pan over a burner set to low to medium-low heat for 2 hours.
The water should be warm enough to indirectly heat the oil, but if it starts simmering and bubbling, it's too hot and should be turned down.
After around 2 hours, remove from heat, cool to room temperature, and cap with a lid.
For a more effective infusion, place the jar in a sunny window for 2 weeks before straining and using.