Using a mandolin, slice beets as thin as possible. Then, using a 1½ or 2-inch cookie cutter, cut slices into even sized circles.
In a small bowl, mix together ricotta, lemon zest, dill and salt and pepper to taste. At this point, you can assemble two raw beets with a dab of ricotta mixture in between. Or, blanch the beet ravioli. Bring a medium pot of salted water to a boil and lower to a simmer. Place a small dab of ricotta mixture between two beet slices and seal, using a little water if necessary.
Blanch a few beet ravioli at a time for a few seconds just to cook, removing onto paper towels with a slotted spoon. Repeat with remaining ravioli. If your beets are not sticking together well, you can blanch the beet slices separately and assemble with ricotta after.
Serve beet ravioli over beet greens. Drizzle with olive oil, lemon juice, salt and pepper. Garnish with walnuts and cilantro and serve immediately.