Preheat the broiler. Bring 1 1/2 cups water to a simmer in a saucepan. Reduce the heat to medium low and stir in the rice, smashed garlic and 1/4 teaspoon salt. Cover and cook until the water is absorbed and the rice is tender, 16 to 18 minutes; set aside.
Meanwhile, toss the poblano, onion, pear, 1 tablespoon olive oil, 1/2 teaspoon salt and a few grinds of pepper on a rimmed baking sheet. Broil, stirring occasionally, until softened and charred in spots, 8 minutes; set aside.
Season the pork with salt, pepper and the thyme. Heat the remaining 2 tablespoons olive oil in a large skillet over medium-high heat. Add the pork; cook until well browned, about 5 minutes per side. Remove to a plate. Add the poblano mixture and sliced garlic to the skillet. Cook until the garlic softens, 2 minutes. Add the broth and cook, scraping up any browned bits, 1 minute. Remove from the heat; stir in the vinegar and half of the cilantro. Season with salt.
Fluff the rice, discard the smashed garlic and stir in the remaining cilantro. Season with salt. Serve with the pork and poblano mixture.