Divide the watercress among 4 soup plates. Dust the cheese slices with flour then dip in beaten egg. Drain and roll in the breadcrumbs pressing gently to evenly coat. Set cheese aside.
Heat 2 tablespoons each of the butter and oil in a saute pan and quickly saute until tomatoes just begin to soften but still hold their shape. Season well with salt and pepper and spoon over watercress.
Add remaining butter and oil to pan and quickly saute Panela until lightly browned and crisp on both sides. Drain cheese briefly on paper towels. Add lemon juice to pan and swirl over high heat to slightly thicken. Season with salt and pepper and spoon over cress. Arrange fried Panela on top and scatter fried capers and/or anchovies over and serve immediately.