Fresh Tuna Sandwich

Ingredients

• 1/2 cup red onion, thinly sliced
• 2 tsp olive oil
• 1 tbsp fennel seed
• 1 cup white wine*
• 1 lb red cabbage, cored and thinly sliced
• 8 oz deli-style sauerkraut
• 1/2 cup rice vinegar
• 1 1/2 tbsp kosher salt
• 1 tbsp wasabi paste
• 4 oz plain nonfat yogurt
• 4 oz goat cheese
• 1 lb high-quality tuna steak (single piece, no blood lines)
• 1/4 cup black peppercorns, cracked
• 1 tbsp kosher salt
• 2 tsp safflower (or canola) oil
• 8 slices rye bread