Sear the tuna for 20 seconds on each side in a hot pan with the oil. The tuna should be seared on the outside and very rare in the middle. Hold at room temperature
For the vegetables: Melt the butter in a small sauce pot and add the 3 vegetables. Cook for 20 seconds and season with salt and pepper. Hold warm.
For the wasabi: Peel off outer bark with vegetable peeler. Grate in circular motion with small hand grater.
For the vinaigrette: Blend mustard and rice wine vinegar with hand blender. Add warm bacon fat. Add soy sauce. Reserve warm
For the sauce: Peel and cut pineapple into small chunks and pass through juicer. Reduce over low heat to syrupy consistency. Reserve at room temperature.
Assembly: Slice the tuna rectangles into 14 equal slices. Arrange 7 on each plate. Place a small mound of vegetables at the top of the plate. Dot each tuna slice with a small ball of grated wasabi. Spoon the bacon vinaigrette along the border of the tuna. Place a spoonful of pineapple sauce at the bottom of the plate.