1. Blend together olives, capers, garlic, mustard, vinegar, the tomato, the water, and salt and pepper to taste and slowly add the oil, blending until it is emulsified. (I use my hand blender.)
2. Stir in the roasted peppers.
3. Season the meat with salt and pepper. Sautée the tuna steaks for 4 to 5 minutes on each side, or until they are just barely cooked through. (if using chicken or pork, cook until done.)
4. Pour the dressing into the skillet, heat, and stir in 2 tablespoons of the roasted peppers and 1 tablespoon of the scallion.
5. Spoon the dressing over the tuna (or other meat) and serve it with the lemon wedges.