A bright and herby sauce, a riff on the classic French sauce gribiche, is an easy way to dress up simple steamed broccolini.
Bring 1 inch of water to a boil in a large pot fitted with a steamer basket over high heat.
Meanwhile, with the motor running, drop garlic through the feed tube of a food processor. Process until finely chopped. Stop the machine and add parsley, lemon zest, lemon juice, capers, scallions and mustard. Pulse until the scallions are finely chopped. Add eggs and pulse until chopped. Add 4 tablespoons oil, 1/2 teaspoon salt and 1/4 teaspoon pepper and pulse to combine.
Add broccolini to the steamer basket, cover and steam, in batches if necessary, until bright green and just tender, about 4 minutes.
Transfer the broccolini to a serving platter. Drizzle with the remaining 2 tablespoons oil and sprinkle with the remaining 1/4 teaspoon each salt and pepper. Top with the sauce.
To make ahead: Refrigerate sauce (Step 1) for up to 3 days.