Place the vegetables and garlic in a roasting pan. Drizzle with oil; toss to coat. Cover and bake at 400F for 20-30 minutes or until vegetables are tender; cool slightly. Remove and chop garlic cloves.
In a Dutch oven, combine the broth, tomatoes, tomato puree, lime juice, chili powder, cayenne, and cumin. Bring to a boil. Reduce heat; simmer, uncovered, for 25-35 minutes or until mixture is reduced by a quarter.
In a large saucepan or Dutch oven, melt butter; stir in flour until smooth. Cook and stir until bubbly and starting to brown. Slowly whisk into tomato mixture. Add roasted vegetables, garlic, beans, and cilantro; mix well. Simmer, uncovered, until chili reaches desired thickness. Garnish with sour cream and green onions if desired.