Separate the leafy parts of the collard greens from the center vein/stem, reserving both. Chop the stem into half-inch pieces, and slice the leaves crosswise into one-inch strips. Finely chop the onion. Cut the poblano into very thin slices then cut the slices into half-inch piecces

Bring a quart of water to a boil in a saucepan, then add the salt and the collard stems. Cook for five minutes. Add the collard greens and stir for about a half-minute. Reserve three-quarters cup of the water, then drain the greens.

In the meantime, warm the oil in a medium-sized sauté pan over medium heat. Add the finely-chopped onion and poblano and stir. Add in the cardamom and continue to sauté, stirring occasionally, for five to ten minutes. The onion should be soft and translucent, and just a bit brown. Add the ginger and garlic and sauté for a minute more. Add the collard greens and stems along with the reserved cooking water, stir, and cook for about five more minutes, until the greens are tender. Adjust seasoning to taste.