For the mashed potatoes, peel and rinse the potatoes and cook in salted water until tender.
In the meantime, peel and finely dice the shallots. Peel the garlic and cut it into thin slices.
Heat some of the olive oil and sauté the shallots and garlic until translucent, then add the remaining oil and heat everything together.
Strain the potatoes, pour the shallot-garlic oil over them, reserving the shallots and garlic with a shallow slotted spoon, and roughly mash the potatoes.
Finally, stir in the pine nuts, garlic, shallots, the chopped tomatoes and the plucked basil leaves, and season vigorously with salt and freshly ground pepper.
Round off with the juice of a lemon.