Reduce heat to medium, add onions, and cook, stirring occasionally, until softened and beginning to brown, 12 to 15 minutes. (If onions begin to darken too quickly, add 1 to 2 tablespoons water to pan.) Add tomato paste and cook, stirring constantly, until it browns on sides and bottom of pan, about 2 minutes. Add garlic and cook until aromatic, about 30 seconds. Increase heat to medium-high and add Guinness. Add broth, ½ of dried figs, carrots, thyme, and bay leaf. Add beef and any accumulated juices to pot; cover and bring to simmer. Transfer pot to oven and cook, using tongs to turn meat twice during cooking, until fork slips easily in and out of meat, 2 to 2½ hours.