VS 2008 Convert A String Into A Linq Query?

Is there a way to convert a string into a linq query? Searching for those words brings up tons of stuff unrelated to what I'm trying to do..For instance, this works, of course...

Dim lstMyQuery = (From item in htMyTable.values where item(0) = "Apple" Select item)

But somehow I want to do this:

Dim strQuery = "From item in htMyTable.values where item(0) = " & CHR(34) & "Apples" & CHR(34) & " Select item"
Dim lstMyQuery = (Somehow run/convert strQuery as a query)

The reason is strQuery will be different each time depending on what the user has selected earlier in the program.R if lstMyQuery is already a collection, is there a way to add to it?

Dim lstMyQuery = (From item in htMyTable.values where item(0) = "Apples" Select item)

(this obviously doesn't work, but it's basically what I want to do...)

lstMyQuery.Add(From item in htMyTable.values where item(0) = "Oranges" Select item)