I think where you're getting mixed up is that there are different kinds of conditions. Normally, when philosophers discuss necessary and sufficient conditions, they mean for the application of a predicate to an individual. For example, What conditions are necessary and sufficient for X (some individual) to be bread (where "being bread" is a predicate). Equivalently: under what conditions, for any X, does X count as bread?
Another kind of condition is causal or circumstantial. This is the kind of condition one means if one asks, what conditions are necessary for fire to start? What conditions are sufficient. When the original question (and Heinrich's answer and PeterJ's comment) discuss conditions, they mean what conditions are necessary for bread to come about, for bread to exist? That is different.
The first (definitional) kind of condition concerns when a predicate can properly be applied to a thing. The second (causal) kind of condition concerns when something can exist.
I am not a baking expert, but to give necessary and sufficient conditions for X being bread, we can say something like:
For X to be bread, it is necessary that it:
- be made with flour;
- be made with water;
- be made with a leavening agent;
- have its ingredients mixed;
- have its ingredients baked.
Each of these predicates is individually necessary for being bread. That means that a thing can't be bread if it lacks any one of them.
These predicates are also jointly sufficient for being bread. That means that anything that meets all of them is bread.
However, there are also many other conditions not on this list which are sufficient for being bread. Being Wonderbread is a sufficient condition for being bread. Being sourdough bread is a sufficient condition for being bread. Being a bagel is sufficient condition for being bread. And so on.