Heat olive oil in a large skillet over medium heat. Sauté the diced onion until translucent, then stir in the minced garlic and dried oregano. This aromatic start builds a savory foundation for this high-protein vegetarian meal.
Add the dry orzo directly to the skillet. Stir constantly for two minutes until the pasta smells slightly nutty and the edges turn translucent. Toasting prevents the orzo from becoming mushy and ensures each grain holds its shape during the simmer.
Pour in the vegetable broth and add the chopped sun-dried tomatoes. Cover and simmer on low for about 10 minutes, stirring occasionally. The orzo will absorb the liquid and release its natural starches, creating a silky, cream-like sauce without any heavy dairy.
Fold in the rinsed cannellini beans. These creamy white beans are an excellent source of plant-based protein and fiber, making the dish hearty enough to serve as a main course. Stir gently to heat them through without mashing.
Add the fresh baby spinach to the pan. The residual heat from the pasta will wilt the leaves in less than a minute. This adds a vibrant pop of color and a boost of nutrients to your one-pot dinner.
Turn off the heat and stir in the Parmesan cheese and fresh lemon juice. The acidity of the lemon perfectly balances the richness of the white beans and cheese. Let the pan rest for three minutes before serving to allow the sauce to thicken into its final, glossy consistency.
