Preheat oven to 425*
Salt all sides of your ribeye and set aside.
In a bowl toss potatoes with olive oil until lightly coated.
Add herbs and salt to taste.
In a baking dish, evenly spread out potatoes into one layer.
In a separate baking dish, add sliced shallots and lightly coat with olive oil and salt.
Place both baking dishes into oven and bake 25-30 minutes until golden brown, flipping halfway through.
In a small bowl whisk olive oil, vinegar, mustard, lemon juice until it emulsifies.
Salt to taste.
Once potatoes and shallot are done set aside to cool.
Meanwhile, prepare the grill.
Once coals are done add steak to hot grill and cook about 4-6 minutes on each side, internal temp should be about 150* for medium.
Pull steak off and set aside to rest for 10 minutes.
Once rested, slice steak against the grain into strips.
Assemble salad by layering watercress and arugula, potatoes, shallots, and tomatoes.
Drizzle dressing over greens.
Top with sliced ribeye and serve!