Step 1

If using rhubarb, dissolve ¼ tsp. salt in 1 cup warm water in a small bowl. Add rhubarb and let soak 5 minutes (doing this will mellow the rhubarb’s acidity). Drain and pat dry. Place in a small bowl with chopped lemon and toss to combine. Let sit until ready to serve pasta.

Step 2

Cook fregola in a large pot of boiling lightly salted water, stirring occasionally, until very al dente, 6–8 minutes. Drain, reserving 1 cup pasta cooking liquid.

Step 3

Meanwhile, heat ¼ cup oil in a large skillet over medium. Cook garlic, swirling around in pan often, until just golden, about 1 minute. Add wine; bring to a boil. Reduce heat and simmer until reduced by half, about 3 minutes. Add cockles, cover skillet, and cook until they open, about 4 minutes. Transfer cockles to a bowl, discarding any that don’t open.

Step 4

Add fregola, ½ cup pasta cooking liquid, and butter to skillet. Cook, tossing often, until fregola is tender and sauce is slightly thickened, about 3 minutes. Mix in basil, chives, and parsley and cook until basil has just wilted, about 20 seconds. Return cockles to pot and cook until warmed through.

Step 5

Divide fregola and cockles among bowls. Drizzle with oil; top with rhubarb-lemon mixture (or just chopped lemon if not using rhubarb) and red pepper flakes.