Step 1Warm the olive oil, lemon zest, cumin seeds and crushed red pepper flakes in a small saucepan over low heat until the lemon zest curls and sizzles, about 10 minutes. Remove from heat and let steep at least 1 hour.
Step 2Strain the oil. Use one-fourth cup in this recipe, saving the remaining oil for another use. It will keep, refrigerated in a tightly covered jar, for 2 to 3 days.
Step 1Blanch the greens, one variety at a time, in rapidly boiling generously salted water until they are tender and bright green, 2 to 7 minutes, depending on the variety. When all of the greens have been blanched, combine them into one mass. Allow to cool enough to handle, then pick up a large clump and squeeze it in your hand to wring out as much liquid as you can. Chop the greens finely.
Step 2Warm the olive oil and the garlic clove in a large skillet over medium-low heat until the garlic becomes fragrant, 3 to 5 minutes. Add the greens and cook, stirring, until no more liquid remains in the skillet, 3 to 5 minutes.
Step 3Add the lemon-cumin oil 1 tablespoon at a time and cook, stirring, until each tablespoon is completely absorbed. Continue cooking until the greens are very soft, about 5 minutes. Stir in the toasted pine nuts and continue cooking 5 more minutes. Season to taste with salt, discard the garlic clove and serve immediately.