Seared Rainbow Chard with Leeks

We've started doing a CSA box and this was the first week. Inside, it had rainbow chard which I've never cooked with before. While searching for recipes, I found this one which also helped with my overabundance of leeks problem (why was the Val-Mont only selling them in packs of 6?!). The original (below) serves 8, we scaled it in half. I was worried it would be lacking in flavour given how few spices it has, but found the resulting dish quite bold ... and perhaps with just a touch too much leek.

Seared Rainbow Chard with Leeks (from epicurious, originally Gourmet)

Ingredients
2 (1-lb) bunches rainbow chard or red and green Swiss chard
3 tablespoons unsalted butter
2 tablespoons extra-virgin olive oil
2 large leeks (white and pale green parts only), halved lengthwise and cut crosswise into 1/4-inch-thick slices
3/4 teaspoon fine sea salt

1. Cut stems from chard (if leaves are large, cut out coarse portions of rib), then cut stems crosswise into 1/4-inch-thick slices. Stack chard leaves and roll into cylinders. Cut cylinders crosswise to make 1-inch-thick strips of leaves.
2. Heat butter and oil in a 12-inch heavy skillet over moderately high heat until foam subsides, then sauté chard stems and leeks with sea salt and pepper to taste, stirring occasionally, until slightly soft, 3 to 5 minutes.
3. Add chard leaves and continue to sauté, stirring frequently, until wilted. (If greens begin to brown before they wilt, sprinkle with a few drops of water.)