Pour the seeds into a food processor or strong blender. If you want them toasted, bake on 350 for 10-15 minutes first.
Add olive oil and process until you reach desired consistency, pausing the machine to stir.
Add salt and herbs to taste.
If the tahini is too thick you can add more oil and adjust.
Refrigerate in a sealed glass container.
Notes
I personally use raw organic 'unhulled' untoasted sesame seeds in this recipe because they're more nutrient-rich. However if you prefer toasted seeds just bake them in the oven on 350 for 10-15 minutes before processing.