Step 1Place the potatoes in a large saucepan and cover them with cold water. Add salt to taste and bring to a simmer. Cook the potatoes until they're tender, about 25 minutes. Drain, let them cool slightly, then peel and coarsely chop them.
Step 2Cut the kale leaves off of their tough stems and chop them coarsely. Bring water to a simmer in a 12-to 14-inch skillet and add a dash of salt. Add the kale and simmer until tender, 7 to 10 minutes, then drain. (If you're using 2 bunches of kale, you'll need 2 large skillets.)
Step 3Heat the oil with the garlic and pepper flakes in a large skillet over medium heat. When you can smell the garlic, add the olives, kale, potatoes and tomatoes. Cook, breaking up the potatoes with a fork and mashing them into the greens to make a kind of rough hash. Taste for salt and serve with olive oil drizzled over the top.