With green mangoes in particular I would eat with salt and pepper sauce, make pickles, salad and like you said cole slaw.
Some of my Guyanese relatives and friends make chutney, achaar/kuchela (masala mixed and shredding green mangos).
Most of the Trini friends i have make chow (pieces of green fruit, culantro, minced garlic and salt, hot peppers, maybe lemon juice)