Cholent is considered a mixture of beans, potatoes, meat, etc. If you dip into cholent with a spoon, you are separating one glob of cholent from another glob. IOW, you are taking a mixture from a mixture. Since what you took is still mixed up, you have not performed "selection" of one type from another. So you have not performed borer at all.
The Shulchan Aruch in O.C. 319 (as another user has already shown) is the source of these laws.
A technical way to look at it, is that borer can only be violated if you separate one "type" from another "type". (see Rema 319) The poskim explain that a type is defined by a piece either having a different taste, or a different name. (see for example Pri Megadim on 319: 5, and 19)
For example, salty crackers mixed with sweet crackers, may look similar and are made from almost similar ingredients and are both called cracker; but they taste different. Also, salami and bologna etc.
OR if they have a different name (or function) like kosher candy mixed with non kosher candy of the same type and flavor (one has a hechsher while the other does not because it has a treif ingredient) or juice oranges mixed with eating oranges. Also, forks and spoons mixed up in a close pile together. Some also say size matters if the item is specifically sold in different sizes. But as shown by another user, 319 tells us that bigger slices and smaller slices of the same thing is not a borer mixture.
So based on this we can easily see that your spoon of cholent as compared to the remaining cholent in the pot you left behind is a) also called "cholent" and b) tastes just like "cholent", so it is not two types being separated at all. Therefore there is no borer.
However, the Taz is of the strict opinion to not allow separating even one type from its own type! But the Mishnah Berurah tells us that many poskim do not agree with the Taz. In any case, the Taz allows you to take what you want (the "good") from what you wish to leave behind (the "bad") as usual. so you can take what you want, with your hand, for use right away, even according to the Taz when taking one type from itself.
(According to everyone then, the way to encounter forbidden borer with cholent is if you do not like potatoes and use a spoon to sift and pick out the potatoes from the cholent mixture in order to discard the potatoes.)
However, how can we say that a Ladel is an extension of (or just like) your hand?
Sefer Shmiras Shabbos K'Hilchasah explains (Ch:3:126) that there are actually 3 ways to use a utensil as merely an extension of your hand (so it counts as "by hand" and not a "kli")
1) Convenience: avoiding getting your hands dirty.
2) You cannot reach deep into the pot without it (The utensil merely facilitates covering distance or accessibility).
3) If the utensil is the only way you can perform the act (like peeling an apple with a regular knife, which is permitted.) In this case, we say that since you would not be willing to take your nails and scratch the peel off, the knife is your only way to eat the apple in a normal manner (without the peel). Therefore, the knife becomes a mere extension of your hand because this is considered "derech achilah" or the way it is normally eaten and is considered part of the eating process.
However, a spoon used for skimming fat off the top of soup is not allowed, since you could pour the fat off without it, but the spoon skimming is a more efficient way of separating the fat off cleanly without wasting as much soup to do it. Since the spoon increases efficiency of borer, it is not considered "your hand". But (as above) if there were no practical way for you to do it except with the utensil (like the apple peel above) then it is considered your hand.
And besides this source, (and what another user gave as a source in Mishnah Berurah 319:24,) it would also help to see Mishnah Berurah 319:55, with Shar HaTzion 319:44; also Igros Moshe Orach Chayim I:124.
I hope this helps. :)
