Originally Posted by Andy M.
I have NEVER heard of gradually bringing something to a simmer. BTB RTS is the standard.
I'll admit I've seen this phrase in recipes. Most notably in recipes involving milk or other dairy, where boiling might cause ingredients to curdle, separate, or burn (examples: stovetop custards or when making cheese). In these cases, rather than setting the burner to high and lowering the heat once it comes to a boil, I've just set the initial temperature lower - say, medium low - and once it comes up to the desired temp, I turn the burner down to low to maintain it.
But no, I've never seen any recipe that calls for gradually increasing the heat source. That seems a little silly.