Wash the lemons hot and grate them dry. Grate the zest of one lemon, halve the lemon and squeeze it. Cut the rest of the lemon into slices. Whisk butter with a whisk of the hand mixer for about 5 minutes until white and creamy.
Remove the avocado pulp from the skin. Coarsely mash half of the flesh with a fork. Mix the rest of the avocado with the blender into the whipped butter. Fold in crushed avocado and lemon peel.
Season butter with salt, pepper, a little sugar and lemon juice. Form butter into a roll with cling film and chill for about 30 minutes. In the meantime, wash the meat and pat dry. Fold the ham lengthwise.
Wash the sage, dab dry and remove coarse stalks. Wrap ham around the meat and wrap sage leaves around it. Season meat with coarse salt and pepper. Fry meat on the hot grill all around for about 15 minutes.
In the meantime clean and wash the tomatoes and cut them in half horizontally. Season the cut surface with coarse salt and pepper. About 6 minutes before the end of the cooking time of the meat, roast the tomatoes on the hot grill.
Arrange meat and tomatoes on preheated plates, add avocado butter and lemon.