Linguine with Mussels and Kale

Name: Linguine with Mussels and Kale
Ingredients: 3/4 pound linguine; Salt; 1/4 cup plus 2 tablespoons extra-virgin olive oil; 1 medium onion, quartered lengthwise and thinly sliced crosswise; 2 garlic cloves, thinly sliced; 1/2 teaspoon crushed red pepper; 2 pounds mussels, scrubbed and debearded; 6 large kale leaves, stems and inner ribs discarded, leaves coarsely chopped