Thoroughly wash 1 bunch of Swiss chard under cool, running, drinkable water. Remove the center stalks with the tip of a knife, cutting along the stalk to where it narrows to about ½-inch thick, or strip it out with your hands. To do this, loosen a bit of the leaf from both sides of the stalk at the bottom of the leaf. Grab hold of the stalk with one hand and gently pull the frayed leaf upward with the other, stripping it away from the stalk. Reserve the stalks.
Next, chiffonade the leaves. Stack several leaves on top of each other, with the largest on the bottom. Roll them up crosswise then thinly slice crosswise from one end of the roll to the other. Set aside.
Thoroughly wash 2 tomatoes under cool, running, drinkable water. Dice and set aside. Dice ½ onion and mince 3 cloves of garlic.
In a large sauté pan over medium heat, add 2 tablespoons of extra-virgin olive oil. Once heated, add diced onion and reserved stalks; cook until softened, about 3 minutes.
Add minced garlic, 2 anchovies, and ¼ teaspoon of crushed red pepper flakes. Cook until the anchovies dissolve, about 1 minute.
Add Swiss chard leaves, 2 tablespoons of capers, and ¼ cup of chopped Kalamata olives. Cook until the leaves have wilted and are tender, stirring constantly, about 5 minutes.
Season to taste with kosher salt if needed (the capers, olives, and anchovies are already quite salty), and serve warm or at room temperature. Eat up, Mama!