Bring a large pot of salted water to a boil.
Add the chopped rapini and cook until softened and bright green, about 3 minutes.
Using a slotted spoon or tongs, remove the rapini from the water and set it aside, leaving the water in the pot.
Return the same pot of water to a rolling boil.
Add the orzo and cook according to package directions until al dente, typically 8-10 minutes.
Drain the orzo well and set aside.
While the orzo cooks, heat the olive oil in a large skillet or pan over medium heat.
Add the minced garlic and cook until fragrant, about 30 seconds, being careful not to let it burn.
Stir in the red pepper flakes and chopped sun-dried tomatoes.
Add the reserved, cooked rapini to the skillet and cook, stirring occasionally, until it is tender, about 5 minutes.
Add the cooked and drained orzo to the skillet with the rapini mixture.
Stir everything together to combine and heat through.
Season generously with salt and freshly ground black pepper to your liking.
Serve immediately, sprinkled with toasted pine nuts.
Don't skip blanching the rapini in salted water. This simple step helps to mellow its natural bitterness, resulting in a more balanced flavor.