Lightly toast sesame seeds on top of the stove over medium high heat, until just barely brown. You don't want to overdo it. Remove seeds from pan and let cool in a bowl for 10 minutes.
Add to high speed blender or food processor (I use the smaller, dry container of my Blendtec), and process for 20 seconds.
Then add oil and salt. Process in increments of 20 seconds, scraping down sides and blending until completely smooth. You can see the stages above of how it will look above. Just keep going, it will get there! This will take about 1 1/2 to 2 minutes depending on the strength of your blender.
Store in glass jar in the refrigerator.
Stir tahini very well before using, as some of the oil can rise to the top and you need to keep that within the mixture.