In medium size pot sauté the onion and leek with olive oil until soft. Add the spinach and sliverbeet, most of the dill (save just a little for garnishing) and 2/3 cup warm water and bring to a simmer. Add the rice, salt and pepper (to taste)and simmer, covered for about 20 minutes until rice is soft. Add additional warm water air needed just to cook the rice, you want the finished dish to be smooth and creamy, not watery.
Serve warm or at room temperature with a squeeze of lemon juice, olive oil and feta. Garnish with a little of the remaining dill.