1head of romaine lettuceabout three cups, roughly chopped and fairly densely packed
juice of one limeor lemon, or use bottled
1-3jalapeñosstems and some pith removed (more seeds and pith=more heat)
Combine all ingredients in a food processor fitted with a metal blade (add the lettuce a handful at a time, pulsing briefly to make more room) and puree until smooth. Taste and adjust for flavor as necessary.