A cozy, lemon-brightened soup where creamy butter beans and tender jasmine rice luxuriate in a well-seasoned vegetable broth, lifted with fresh thyme and sweet roasted peppers. Comforting yet vibrant, it finishes with a citrusy flourish of thin lemon slices.
Thinly slice 1 lemon (peel on) and remove any seeds; set aside.
Heat olive oil in a large pot over medium-high heat. Add the chopped onion and cook until golden around the edges, about 5 minutes.
Add carrots, celery, garlic, thyme, and salt; cook, stirring frequently, for about 2 minutes to soften slightly.
Add roasted red peppers, vegetable broth, and half of the lemon slices. Partially cover and bring to a boil.
Stir in jasmine rice and butter beans. Reduce heat to medium-low, partially cover, and simmer until the rice is tender, about 15 minutes.
Remove from heat and stir in baby spinach. If desired, thin with a splash of broth or water. Season with additional salt and black pepper to taste.
Ladle into bowls and garnish with the remaining lemon slices; serve.