Wash your toy with plain soap and water to remove any lube and residue and dry with a soft cloth or paper towels. What type of soap you use will depend on the type of lube you use. J-lube for example rinses off easily with a mild dish detergent. Grease based lubes will need something with grease cutting power. Silicone lubes are the most persistent and will need something as strong as Dawn® dishwashing detergent to remove. Soaking them is ok as silicone is a hydro-phobic material and will not absorb water, just do not soak your silicone toys with those made of vinyl as the plasticizers will migrate in the water and could damage them.
Putting your silicone toys in the dishwasher isn’t always the best way to ensure they get clean, but they will certainly withstand the heat of the cycle with no issues. But just like fine china, the abrasive action of the inside of a dishwasher can dull and pit the surface of your toys over time.
First, there are varying levels of sterilization that might be required. Most of you I find are just wanting to kill germs. As I am not a doctor, I can only advise you on what type of techniques will not damage the structural integrity of your toys. Certain viruses need pressure along with heat to destroy them. As a rule I do not share butt toys so my sterilization experience is only for cleanliness.
The silicone I use can safely withstand heat up to 400 °F. In fact, I have placed them in the oven to test this. Place them upright on a glass baking dish or line any pan with aluminum foil and bake. Don’t worry about them going limp, they will still be the same firmness going out as they were going in, one reason silicone is so widely used in temperature dependent industrial applications today.
Boiling is also an option as water will not harm the material. Recommendations for boiling would be to stand them upright on a grate in a tall pot. Because silicone is such a good insulator they should be off the bottom as heat can build up and damage your pan or the toy. They should have water freely flowing around them at all times as well. It follows as well that they are completely dishwasher safe, top or bottom rack. Just keep them upright so they don’t pick up any impressions from the racks.
The widely accepted 10 minute soak in a 10% bleach solution won’t hurt them either. Just be sure the toys are free of lube. This is not a good method for silicone lube covered toys as it maintains a film on the toy.