How to Make It
Heat a large skillet over medium-high heat. Add walnuts; cook 5 minutes or until toasted, stirring occasionally. Remove walnuts from pan; coarsely chop.
Add oil to pan; swirl to coat. Sprinkle chicken evenly with 1/4 teaspoon salt and 1/4 teaspoon pepper. Add chicken to pan; cook 4 minutes or until browned. Turn and cook 3 minutes. Place chicken on a plate (chicken will not be cooked through). Add rice, onion, carrot, celery, and thyme to pan; cook 3 minutes, stirring to coat rice. Add remaining 1/4 teaspoon salt, remaining 1/4 teaspoon pepper, stock, and 1 cup water, scraping pan to loosen browned bits. Reduce heat to low; cover and simmer 45 minutes. Return chicken thighs to pan, nestling them into rice mixture. Top with raisins and Brussels sprouts. Return to a simmer; cover and cook 12 minutes or until liquid is absorbed and chicken is done. Place chicken on a platter. Stir walnuts and vinegar into rice mixture. Serve rice mixture with chicken.