Ina Garten's Bean and Arugula Salad - almost the same ingredients, slightly different method

I am reluctant to alter anything about the recipes contained in Ina Garten's Foolproof cookbook, for an obvious reason...they're foolproof. However, I confess to using tinned rather than dried and reconstituted beans to make this salad. What can I say....I only have so much time to cook. The tin canning process was allegedly created by Frenchman Philippe de Girard and the idea passed to British merchant Peter Durand who patented Girard's idea in 1810. Once they got rid of the lead soldering in the cans, people stopped dying, and canned goods took hold. Of note, tinned vegetables frequently contain a lot of salt, so a reduction of the amount of salt that Ina recommended in this recipe was essential. 

Ingredients:

• 2 tins of cannellini beans

• 2 tablespoons plus an additional 1/4 to 1/2 cup good olive oil

• 1 red onion, halved lengthwise and sliced into 1/4-inch-thick half-rounds

• 2 ounces sun-dried tomatoes in oil, drained and small-diced

• 4 teaspoons minced garlic (4 cloves)

• 2 teaspoons minced fresh rosemary leaves

• 1/4 teaspoon crushed red pepper flakes

• 2 ounces thinly sliced prosciutto, small-diced

• 1 teaspoon grated lemon zest

• 1/4 cup freshly squeezed lemon juice 

• Kosher salt and freshly ground black pepper to taste

• 2 ounces baby arugula

Methods:
Remove the beans from their tins, rinse and drain them well. Saute the red onions in 2 tablespoons of olive oil over medium-low heat until soft. Add the rest of the olive oil to the saute pan along with the sun-dried tomatoes, garlic, rosemary, red pepper flakes, and prosciutto and cook for 4 to 5 minutes. Pour the hot oil mixture over the drained beans, tossing well. While still warm, stir in the lemon zest, lemon juice, and salt and pepper to taste. Place the bean mixture in a large serving bowl, surrounded by the arugula. This salad can be served warm or at room temperature.