1. In a large nonstick skillet, arrange prosciutto slices in a single layer without overlapping. Cook over medium heat for 4 to 5 minutes or until brown and crispy, turning frequently. Drain on paper towel; break into large pieces. Reserve drippings in skillet.
2. To blanch beans, bring a large saucepan of lightly salted water to boil; add beans. Gently boil for 2 to 3 minutes or until beans turn bright green and just begin to become crisp-tender. Immediately drain in a colander and transfer to a large bowl of ice water to stop cooking.
3. Drain beans and dry well. Transfer to a large serving bowl. Add tomatoes, onion and prosciutto; set aside.
4. In a small bowl, whisk together prosciutto drippings, olive oil and lemon juice. Pour over vegetable salad mixture and toss to coat. Season to taste with sea salt and black pepper.

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For individual picnic salads: Transfer tossed salad to small storage-and-canning jars. Close with lids and pack in an insulated cooler with an ice pack.