Combine all ingredients in a pourable container. Stir to thoroughly emulsify. Set the dressing for several hours before preparing the salad so the flavors can marry. Can be prepared up to 48 hours in advance.
Hard-boil the eggs, peel, and refrigerate until salad assembly.
Slice the red potatoes into 1/4 inch pieces and cook 4 to 5 minutes or until cooked through in a 4-6 quart pot. Don't overcook or the potatoes will fall apart. Strain, rinse with cold water, and sprinkle apple cider vinegar on them. Cover and store in the refrigerator.
For the green beans, cut off the ends, cut to size, and boil in salted water for 3-5 minutes or done to taste, closer to al dente. Strain and store in the fridge
Coat the tuna with grapeseed oil and then rub with a spicy tuna rub - one of many varieties found at the grocery store. I used the Tom Douglas Spicy Tokyo Rub product.Heat grill to 600 degrees to properly sear the tuna steak. Sear each of the four sides of the tuna for 2-3 minutes, or even less depending on how rare you prefer your tuna. Remove from heat and let rest for five minutes. Slice into 1/2 thick pieces.
To assemble the salad, combine the greens, potatoes, green beans, tomatoes, olives, and verts in a large mixing bowl.
Stir the vinaigrette to remix after it has been stored in the fridge. Drizzle the salad with enough vinaigrette to fully coat and toss gently. Season to taste with salt and pepper.
Take care not to bruise the ingredients - the critical element for an outstanding nicoise salad is that it is arranged on a platter with all the ingredients keeping their individual integrity and in groups. Store salad for at least 15 minutes to soak the dressing before adding the tuna.
Arrange the tossed salad down the center of a serving platter and lay the seared tuna attractively across the top and the eggs around the rim. Serve.