Slashing bread doughCareful slashing or scoring of the dough's risen surface with a razor, called a “lame” (pronounced “lahm”), creates “bursts” or serves the purpose of allowing the dough – which experiences a very rapid final rise in the oven, called “oven spring” – to expand into a pre-determined shape. They are also decorative. This is done on many artisan breads. You can also use sharp scissors with some recipes. A single edged razor also works well as long as you use the front tip of the razor.

If slashes are not done in certain recipes, the expanding gasses in the bread from oven spring would find weak points in the surface and create a torn, lumpish, unattractive bread. The French have given a name to this portion of expanded dough: They refer to it as la grigne, or “the grin” of the bread. Slash your bread AFTER applying the glaze (such as egg wash) so there is a more dramatic contrast between the interior and the exterior of the bread. After slashing your bread, sprinkle any seeds or toppings on your recipe. Waste no time in getting your bread into a hot oven to bake.
SARAH SAYS: When slashing fully proofed (risen) dough, in these cases, it may collapse. You want to catch it when it is almost risen as the bread will then spring in the oven and bloom open at the cut points!

This how to baking technique is used with the:
Stromboli Recipe Tutorial

HOW TO TIPS:
1. Brush the ALMOST risen dough with the egg wash.

2. Cut two to five shallow diagonal cuts across the bread with a bakers lame (a very handy little tool!) or with the tip of a single edged razor. You can also make a long
This is called slashing or scoring bread dough.
WIth diagonal cuts, the end of the last diagonal is where you should start the next one.
SARAH SAYS: Hold the knife blade at a shallow angle (about 45 degrees) to the bread's surface, so that you slit under the surface of the dough.
Slash your bread about 1/4-inch deep, rather than too deeply. If you score the bread's surface at an angle, the edges will both remain separate and expand away from each other; if cut vertically, the edges tend to collapse towards one another and close again.

 
3. If desired, sprinkle the bread with sesame seeds. Put it into the oven right away.