Oxalis sanmiguelii ssp. urubambensis
When grown hard like a succulent (low nutrient, full sun, and little water) the plant often drops a number of leaves and store more water in the petioles, causing it to become plump and delicious. At night it also pulls all of the leaves and petioles together. It gets a little larger in the ground. ;)
This species is known incorrectly under several other names like O. peduncularis, O. herrerae and O. teneriensis.