Thinly slice the cabbage in a food processor using the 4mm slicing disk or by hand; you should have about 6 packed cups. Put the cabbage in a colander and toss it with 1 Tbs. kosher salt. Lay a plate that fits inside the colander on top of the cabbage and set a heavy can or jar on top of the plate. Drain the cabbage in the sink or over a bowl for 2 hours.
If using a food processor, switch to the grating disk and grate the jícama or cut it into very thin (julienne) strips by hand; you should have about 2 cups. Put the jícama in a large bowl and toss in the scallions and cilantro.
In a small bowl, whisk the mayonnaise, lime juice, and jalapeño.
Turn the cabbage out onto a clean dishtowel or paper towels and pat it thoroughly dry. Toss the cabbage with the jícama and the lime mayonnaise. Season to taste with more kosher salt and lime juice if needed.
nutrition information (per serving):
based on eight servings;
Photo: Scott Phillips