Heat the olive oil in a large, deep skillet over medium. Cook the onion 3 to 4 minutes, until soft, then the garlic for 30 seconds.

Stir in the orzo and toast it 1 minute — this small step keeps it from going gummy.

Add the tomatoes with their juice, the broth, oregano, red pepper flakes, salt, and pepper. Simmer uncovered 10 to 12 minutes, stirring now and then, until the orzo is nearly tender.

Nestle the shrimp into the orzo, scatter the feta over the top, cover, and cook 4 to 5 minutes, until the shrimp are opaque.

Off the heat, add the lemon zest and juice and the parsley. Rest 2 minutes — the orzo drinks up the last of the broth.