This is a rich, hearty dish with plenty of typical Thai flavors.
Any kind of beef may be used, but flank steak works particularly
well because it is easy to cut it across the grain, which helps
keep the meat from falling apart during stir-frying and produces
a tender result.  Be sure to serve plenty of rice, because it
helps moderate the hot chilies without detracting from the
flavor.  You may reduce the number of chilies by up to one half,
but traditionally this dish should have a rich, hot chili flavor.

Serves 4 to 6

1 pound flank steak

14 (2 ounces) finely chopped Serrano chilies
1/4 cup (2 ounces) finely chopped garlic
1/2 cup (2 ounces) finely chopped yellow onion

1/4 cup + 2 Tablespoons vegetable oil

3 tablespoons fish sauce
1 tablespoon granulated sugar
1/2 cup water (more if needed in Step 5)
1/2 cup loosely packed mint or basil leaves

Green lettuce leaves

1.  Slice the beef across the grain into strips 1/4 inch thick
and 2 to 3 inches long.  Set aside.

2.  Pound or grind the chilies, garlic, and onion to a coarse
paste in a mortar or blender.  If you use a blender you may need
to add the oil to aid in grinding.

3.  Heat a wok, add the oil, and swirl it over the surface of the
pan.  (Do not add more oil if you have ground the chilies, onion,
and garlic in oil.)  Add the paste from Step 2 and stir-fry until
it is light golden.

4.  Add the beef and stir-fry until it is a uniform tan color,
but do not overcook it.

5.  Add the fish sauce, sugar, water, and mint (or basil) leaves.
More water may be added if the sauce is too dry.  There should be
about 1/2 to 3/4 cup sauce, depending on how much water you
added.

Ahead of time note:  The dish may be prepared a day in advance to
this point.  To do so, proceed through Step 5, omitting the mint
or basil leaves.  When you are ready to serve, heat the mixture
and add the leaves.  If the meat has absorbed the liquid, add
just enough warm water to bring it back to the original
consistency.

6.  Arrange a single layer of lettuce leaves in a serving bowl
and put the beef mixture over them.  Serve the beef immediately
or keep it warm while preparing other dishes.

7.  Serve with rice.