1 pound flat iron or tenderloin steak, cut in 16 pieces
1 onion, quartered
1 green pepper, seeded and cut in 2 inch pieces
8 Brussels sprouts, halved, or half head of cabbage, chunked
8 pieces fresh pineapple, cut in 1 1/2 inch pieces
8 slices jalapeño chile
Toasted levain or sourdough bread cubes
Prepare Le Gruyère Sauce: Warm milk in medium saucepan. Using a fork, make a roux by mashing butter with flour. Whisk into roux for 1 minute to thicken mixture. Add the two cheeses and continue whisking until cheese melts. Stir in horseradish, mustard, beer, lemon juice and salt and pepper. Keep warm.
Prepare 8 Kebabs: Place 8 skewers on work surface. Skewer piece of steak on one and skewer over an onion quarter, a bell pepper piece, a Brussels sprout (or cabbage chunk), a second steak piece, pineapple piece and jalapeño slice. Repeat with 7 remaining skewers. Salt and pepper to taste.
Prepare grill. Grill kebabs on all sides to desired doneness. Serve with lightly toasted cubes of levain or sourdough bread and the warm Le Gruyère cheese sauce.