With a vegetable peeled, peel the celtuce. You will notice that after one round with the vegetable peeler there is still a layer of light colored stem, peel the celtuce again to remove this, it's very stringy and hard.
Continue peeling the celtuce until only the light green, translucent core remains, then cut the core into 2 inch pieces.
Heat the vegetable broth in a 3 qt or similar sauce pot and season to taste with salt. add the celtuce and cook for 10-15 minutes, or until tender when pierced. Do no over cook the celtuce, or it will fall apart.
Remove the celtuce from the broth and dry. Up to here this can all be done hours, or days beforehand.
Heat the butter in a saute pan. When it begins to brown add the celtuce and cook, turning occasionally, until lightly browned on each side. Remove the celtuce from the pan and keep warm while you quickly cook the leaves.
Add the reserved leaves to the pan and toss, just long enough to wilt, 30 seconds or so.
Place the leaves on the plate, top with the celtuce stems, then add the lemon to remaining butter in the pan, swirl to warm through. Drizzle on some of the lemon butter and serve immediately, finishing with a touch of salt.