Remove the stems from your jalapenos. Using tongs, hold the peppers over a stove burner and rotate until roasted, about 1 minute. Delicious, but not necessary.
Slam your head of lettuce down on the counter stem side down. Pull on the stem to remove the heart and discard. Rip the head of lettuce apart - don't be gentle!
Place lettuce and one or two of the roasted jalapenos into a blender or large food processor. Blend on low speed until jalapenos are pleasantly ground up. Add the mayonnaise, and pulse until blended in. Gradually blend in bread cubes until you get a nice thick but still pourable consistency. If it gets too thick add more mayonnaise. Taste, and blend in more peppers if desired.
Put in a squeeze bottle and serve with your favorite dishes, like Saltado de Pollo, or simply dip your bread in it.