1. Heat 1 tablespoon oil in a medium saucepan over medium heat. Add the garlic, chiles and chard stems and saute until the vegetables soften, stirring to prevent the garlic from browning, 3 to 4 minutes. Sprinkle with 1/4 teaspoon salt. Add the stock, lentils and thyme and bring to a boil. Reduce the heat and simmer, uncovered, adding more stock if necessary to keep the lentils barely covered, until most of the liquid has reduced and the lentils are tender but firm to the bite, about 20 minutes. Remove the thyme sprigs. Add the chard leaves and stir until wilted, about 2 minutes. Remove from the heat, drizzle with the red wine vinegar and 1 tablespoon oil. Season with salt and pepper.
2. Prepare a charcoal grill with a high fire. Rub the onions with about 1 teaspoon of oil and sprinkle with salt and pepper. Place over direct heat. Grill until charred and soft, about 15 minutes.
3. Meanwhile, rub the chops with the remaining 2 teaspoons oil and sprinkle with 1/2 teaspoon salt and 1/4 teaspoon pepper. Place over direct heat and grill until lightly charred and golden brown, and the internal temperature reads 140 degrees F, 8 to 10 minutes per side. Let rest 5 minutes.
4. Serve the pork chops with the braised lentils and grilled onions on the side.