Over medium heat, toast sesame seeds for about 4 minutes until they start to brown and become aromatic.
Move seeds to a blender, blend into a paste, then gradually add oil to reach desired consistency.
Store in an airtight container in the fridge for up to 1 month.
Notes
Add more oil in small increments if you prefer a smoother, thinner tahini.
Sesame seeds can quickly go from perfectly toasted to burnt; pay close attention when toasting. If the sesame seeds brown too much, the tahini may become bitter. Aim for a light golden color for a balanced flavor.