Heat olive oil in a large saucepan over medium-high heat. Add onions. Saute, stirring occasionally, for 2-3 minutes or until the onions are soft and translucent.
Add garlic. Saute, stirring, for about one minute or until fragrant. Add spinach and dill. Season with salt and pepper.
Once the spinach is wilted, add vegetable stock (broth), rice, parsley and lemon juice.
Bring to a boil. Reduce heat to low. Cook, covered, for 5-6 minutes or until the water is absorbed and rice is tender. (Cooking times may vary depending on the type of rice used. Remember to check the package instructions)
Remove from heat. Leave it covered for 10 minutes.
Garnish with feta and chopped dill or parsley.