How to Make It
Preheat the oven to 450°. Line a baking sheet with aluminum foil.
Combine the broccoli, 2 tablespoons of the oil, and the salt on the prepared sheet and toss to evenly coat. Roast until golden and tender, stirring halfway through, about 20 minutes.
Meanwhile, combine the lemon juice, mustard, eggs, and 1 tablespoon of water in a food processor and pulse to combine. With the machine on, slowly drizzle in the remaining ¼ cup of oil until the dressing is smooth. Stir in the capers and dill. Scrape half of the dressing into a large bowl. Add the warm broccoli, beans, and spinach and toss to coat. Transfer to a serving platter and serve warm, sprinkled with more dill, with the remaining dressing on the side.