Rinse the rice under cold water at least three times, or until the water runs clear, then drain in a fine-mesh sieve.
Heat the vegetable broth in a small saucepan until simmering or microwave until steaming; keep hot.
Place a large skillet or shallow pan with a lid over medium heat and add the oil and butter; melt together.
Add the orzo to the melted butter and oil, stir to coat, and toast for 4–5 minutes, stirring occasionally, until the orzo is golden brown.
Lower the heat to medium-low, add the chopped onion, and sauté gently for about 4 minutes until softened.
Add the chopped garlic and the rinsed rice, stirring until the rice turns bright white and is well combined with the orzo and onion.
Pour in the hot broth, add the salt and pepper, and bring the mixture to a gentle simmer.
Reduce heat to low, cover tightly, and simmer for 20–25 minutes, or until the rice is tender and the liquid is absorbed.
Remove the pan from heat and let the pilaf stand, covered, for 5–10 minutes without lifting the lid.
Uncover, fluff the pilaf with a fork, sprinkle with lemon juice, and serve.