Heat chicken broth in a saucepan over medium heat.

Add rice to the broth and simmer for 10-12 minutes, or until the rice is slightly tender.

In a separate skillet, heat butter and sunflower seed oil over medium heat.

Add chopped onions to the skillet and cook, stirring constantly, for 15-20 minutes, or until golden brown and caramelized.

Reserve about 1 tablespoon of the caramelized onions for garnish.

Spoon the remaining caramelized onions into the simmering broth.

In a bowl, mix yogurt, lemon juice, and salt.

Whisk flour into the yogurt mixture until smooth.

Blend the yogurt mixture with 1 cup of the broth (free of onion and rice) in a blender until smooth.

Pour the blended yogurt mixture into the simmering broth.

Bring the mixture to a boil, then reduce heat and simmer for 2-3 minutes, or until the flavors have blended.

Garnish with the reserved caramelized onion and toasted pine nuts before serving.