In a medium jar, combine the Dijon mustard, Italian seasoning, red wine vinegar, garlic, lemon juice, salt, black pepper, and olive oil. Top with lid and toss to combine.
Build the Salad:
Place the chopped lettuce into 2 serving bowls or one large salad bowl. Top with cherry tomatoes, steamed green beans, potatoes, canned salmon, eggs, and olives, making rows of each ingredient.
Drizzle the salad with the vinaigrette and serve.
Leftovers & work lunch:
Refrigerate salad dressing leftovers in an airtight container up to 1 week. Store salad leftovers, without having been tossed in dressing, in an airtight container for up to 3 days.
If meal prepping this salad for a work lunch, layer all the ingredients in an airtight container, pack the dressing separately, and keep refrigerated until ready to serve. Drizzle the salad dressing right before eating it.