Grind toasted sesame seeds into a paste in a mortar (or in a grinder).
Add sesame oil and peanut butter. Mix until well combined.
Grind toasted sesame seeds to a smooth paste in a mortar (or in a grinder).
Add sesame oil then mix well.
Please be aware that there are two types of sesame oil. On my blog, sesame oil always refers to Toasted Sesame Oil (or Pure Sesame Oil/麻油/香油) which is made from toasted sesame seeds. It has a brownish-orange colour and a distinctive nutty aroma. The other type of sesame oil is made from raw, pressed sesame seeds. It has a light golden colour and doesn't have a strong smell. Usually it's labeled as "Sesame seed oil".
3 substitutes for Chinese sesame paste by Red House Spice