Cut the chard crosswise into 1/2 inch slices. In a large skillet, heat the oil on medium high. Add the onion and cook, stirring frequently until golden brown but still crunchy, about 5 minutes. Add garlic and red pepper flakes and stir for a few seconds, until aromatic. Add broth, salt to taste and the greens. Reduce heat, cover, and cook greens until tender, about 5 minutes.

Uncover pan and raise the heat to medium high and cook, stirring continually until mixture is nearly dry.

Serve with warm corn tortillas, crumbled cheese, salsa, cilantro and raw sliced onion rings.