Heat half of the olive oil in a frying pan. Saute the onion, garlic, tomato and tarragon just until fragrant. Add the cabbage, sprinkle with salt and pepper, and cook, stirring occasionally, until the cabbage wilts and the water it has expelled has almost evaporated. Transfer the contents of the pan to a bowl.
Heat the remaining half of the olive oil in the same pan. Add the shredded pork and sprinkle with salt, pepper and sugar. Pour in the kalamansi juice, stir and cook until the meat is camelized and the edges lightly crisp. Transfer the pork to the bowl with the cabbage. Stir. Taste and adjust the seasonings, if needed.
Crack the eggs into the bowl with the cabbage and pork. Stir. Pour everything back into the pan. Cook over low heat, covered, for 10 to 12 minutes or until firm.
Invert the pan onto a plate to release the frittata. Serve hot.