For the salad:

1. Set water to boil in a medium pot and gather eggs, string beans, and potatoes.
2. Using a spoon or tongs, place eggs in boiling water for 10 minutes. Remove eggs and set in ice-water bath to prevent further cooking. Keep water boiling.
3. Place potatoes in boiling water for 15 minutes. Remove and set aside to cool. Keep water boiling.
4. Place string beans in boiling water for 2 to 3 minutes. Remove and set aside to cool. Discard water (cooked ingredients may be stored in the fridge for 24 hours).
5. As above ingredients cook, assemble remaining items: remove seeds and core from bell pepper, cut 1/2 the pepper into thin strips, and cut strips in half. Thinly slice 1/8 red onion. Gather capers, dill, olives, tuna, and lettuce mix.
6. Peel eggs and cut vertically (from pole to pole) into quarters.
7. Place spinach/arugula mix into salad bowl, then layer in all ingredients. If making ahead, store covered and add dressing when ready to eat.

For the dressing:

1. Combine all ingredients in a resealable food storage container. Add lid and shake vigorously to emulsify/thoroughly incorporate all ingredients. Then, simply store dressing in container until salad is ready to eat.