Culinary oils
For food, I wouldn't use infused herbal oils.
While the principle of making your own herbal oils is included in the salve-making articles on this blog, infused herbal oils aren't really suitable for eating.
Traditionally, infused oils are made by cramming herb into a jar, topping up with oil, and letting things stand on a sunny windowsill for weeks on end.
I wouldn't use any windowsill-infused oil in my food. I don't even use such oils in my salves, and salves are more forgiving than salads.
Sure, you could use the waterbath method to make, say, an infused oil with dried rosemary, thyme, and basil, but the taste will be better if you use fresh herbs, and that's likely to rot if you let the fresh herb sit in the oil for too long. There'll be water in your oil even if you strain things out.
Fresh garlic in oils that stand around is right out, because you find Clostridium botulinum in the ground -- where garlic grows. Anaerobic bacteria, oil and water. Yum ... not. The toxin of botulinum is indetectable by taste, sight or smell, and it might kill you (if you're lucky), or paralyze you (if you're not).
No, if you want to use herbs to flavor an oil that you're going to use in your cooking, you'd best chop up a few tablespoons of fresh herb, mix with your oil, let sit in the fridge for a few hours, and use it all within a few days.
That'll get around all of the potential herbal-oil troubles that I know of, including the oil going rancid or rotten on you before you've even gotten around to strain the herb out, the herb going moldy -- and botulism.
jr: yes, that's another
jr: yes, that's another silliness. A couple years ago a pal made hundreds of bottles of herbal oil, just by putting oil and sprigs of herb into pretty bottles, and all of them grew ... something, in no time at all. She had been planning on selling them, but threw the lot away instead.
Those pretty bottles with sprigs in them in the store? That's likely vinegar, not oil, because twigs of herb in oil just isn't practical.
Rose: thanks for that idea!