Pat beef dry with paper towel. In a large heavy-bottomed pot or sauté pan, combine cabernet and bouillon and whisk to dissolve. Bruise garlic with the side of a knife and add to pan with onion, oregano, thyme, peppercorns and bay leaf. Bring the mixture to a gentle simmer, then lower heat until only a few small bubbles are visible on the surface. Add beef and cook for 5 minutes on each side for medium rare, 7 minutes a side for medium well. Transfer cooked steak to a platter and cover to keep warm while cooking beans.

Stir Dijon mustard into poaching liquid and add haricots verts. Cook for 3 minutes or until beans are just tender and transfer to a platter. Cover to keep warm. Bring liquid to a vigorous simmer to reduce poaching liquid by half, about 5 minutes. Meanwhile, transfer beef to a cutting board and slice very thinly, against the grain. To serve, divide haricots verts among four plates and top with thinly sliced beef. Drizzle with a bit of the reduced poaching liquid, garnish with a few of the poached onions, pepper and salt.