In a medium or large pot with a lid, melt 2 tablespoons of the butter over medium heat (optional: brown the butter for a boost of toasty flavor). Add the chopped green onions (white and green parts, reserving a few green parts for garnish if desired) and sauté over medium heat until softened a bit (about 2 minutes).
Add the orzo (1 cup) and the lemon zest (about 1 teaspoon) and stir to coat in the butter. Continue to cook, stirring occasionally, for about 2 minutes, until orzo is slightly toasted from the butter.
Add the chicken stock (2 cups), the kosher salt (1/2 teaspoon), and the black pepper (1/4 teaspoon). Bring to a boil, cover, and simmer on low until all liquid is absorbed, stirring occasionally (about 10 minutes).
Turn off heat and stir in the lemon juice (about 2 tablespoons), the fresh chopped dill (2 tablespoons), and the remaining 1 tablespoon butter until butter is melted.
Season to taste and serve, garnished with more dill and green onions, if desired.
Notes
For a vegan version, use a vegan butter substitute or olive oil.
For a dairy free version, use any vegan substitute or ghee instead of butter.
Ingredient substitutions: parboiled rice may be substituted for half or all of the orzo, parsley may be substituted for the dill, yellow (or similar) onion may be substituted for green onions.