Hello from JustAnswer.
The reason that there is no website with such a diet program is that there is no solid evidence that such a program is effective.
The usual dietary recommendations for someone with an essential tremor is the avoidance of cafffeine and alcohol. For example, see www.mayoclinic.org/diseases-conditions/essential-tremor/manage/ptc-20177888. However, evidence for a specific dietary intervention beyond this is limited, so is not typically recommended.
In review of the medical literature, there is some preliminary evidence that a high protein diet is associated with an increased risk of developing an essential tremor, particularly in men (for example, see www.ncbi.nlm.nih.gov/pubmed/18382115), but there is not a similar study that shows that someone that already has an essential tremor will see improvement in symptoms by following a low protein diet. There also is a study that shows a lower risk of developing an essential tremor in someone that follows a Mediterranean diet (see www.ncbi.nlm.nih.gov/pubmed/18043001), but no study that shows that someone that already has an essential tremor will see an improvement in symptoms by following a Mediterranean diet.
There is no evidence in the medical literature to support any effectiveness of herbal supplements.
So, if you would like valid recommendation from a website that is NOT connected to some fly-by-night company, the Mayo web site is excellent, but will usually only include recommendations that are supported by good clinical evidence.
However, if you would like to try a dietary intervention that has some evidence, it would be reasonable to follow a low protein diet or a Mediterranean diet. There are also other health benefits associated with a Mediterranean diet, such as reduced cardiovascular risk, so it would not be wasted effort. There are many resources for following a Mediterranean diet, including web pages (authoritynutrition.com/mediterranean-diet-meal-plan/) and numerous books (such as https://www.amazon.com/Mediterranean-Diet-Beginners-Complete-Delicious/dp/1623151252/ref=sr_1_1?ie=UTF8&qid=1475794777&sr=8-1&keywords=mediterranean+diet and https://www.amazon.com/Complete-Mediterranean-Diet-Everything-Delicious/dp/1939529956/ref=sr_1_3?ie=UTF8&qid=1475794777&sr=8-3&keywords=mediterranean+diet)
If I can provide any clarification, please let me know.