Peel the black salsifies, cut off the ends, then place in 1 litre of water with vinegar for about 20 minutes. Peel shallots and garlic, chop finely. Peel carrots, cut into cubes. Clean and wash spring onions, cut into diagonal pieces. Chard clean, wash, cut leaves into strips. Drain black salsifies, cut into bite-sized pieces.
Heat oil. Steam shallots, garlic, carrots and black salsifies in it at medium heat for about 7 minutes. Dust with curry and flour, sauté briefly and salt a little. Deglaze with white wine and stock while stirring, cook for another 7 minutes. Add cream, chard and spring onions, cook for 5 minutes. Season to taste with salt, pepper and lemon juice and serve