In a bowl, whisk together the flour, 1/4 liter (approximately 1 cup) of water, the beer, eggs and salt until smooth. Cover and let stand 30 minutes.
Peel the onions and cut into wedges. Rinse the pepper, halve lengthwise, remove the seeds and white ribs and cut into strips. Rinse the celery, remove the strings and slice on the diagonal. Clean the mushrooms with a damp cloth and slice. Rinse the sprouts.
Heat some oil in a pan and sauté the vegetables, stirring occasionally for 5 minutes. Add the sprouts, cook for another 3 minutes. Season with soy sauce and pepper.
Heat a little fat in a pan, pour in a 1/4 of the batter and gently swirl the pan until the batter covers the bottom in a thin layer. Cook over medium heat until lightly browned on the underside. Flip the crepe over and cook until the underside is lightly browned. Repeat with the remaining batter to make 4 thin crepes. Keep warm.
Arrange the crepes on plates, top with the vegetable filling and fold over. Serve.