1. Pour 2 liters (8 cups) water into a cocotte or Dutch oven. Add the vinegar, bouquet garni, coarse salt, peeled and sliced onions and carrots. Bring to a boil and cook gently for 1 hour. Let the broth cool.
2. Bring a large pot of salted water to a boil and add the lamb tongues. Cook for 10 minutes and drain. Skin while still warm. 
3. Return the skinned tongues to the pot and cover with the broth. Bring to a boil; reduce the heat, cover and cook gently for 1 1/2 hours. 
4. Drain, cool and cut into cubes. Transfer to a bowl and combine with the chopped basil. 
5. Cook the asparagus in boiling salted water for 5 minutes. Drain and cut into short lengths. 

Assembling the terrine

1. Prepare the terrine by pouring 1 cm (1/2") aspic into the bottom of the mold and letting it set.
2. Add the confit tomatoes, pour on more aspic; then add the cubes of tongue and basil; add more aspic; finish with the asparagus.
3. Pour on the rest of the aspic and place in the refrigerator to set for at least 24 hours before serving.