Blending a smoothie without changing the taste

You actually made me look up „smoothie“ because I wanted to double-check for some kind of definition.
^_^

Your current ingredient list is

• Mango, frozen
• Ice cubes

If you throw that in a blender (provided yours is powerful enough, many are), you get some kind of ice slush - like a frozen smoothie. The trivial suggestion would be to use water instead of ice (substituting all or some of the ice cubes), but you ruled that out as tasting too watery - unless this already solves your problem. Using (softened/thawed) mango alone will probably be too thick, but it’s a matter of taste.

Personally, I am not the greatest fan of adding plain water or too much ice, simply for the reasons you stated: it can be a too prominent taste, especially if the water isn’t “tasteless” from the beginning, which is the case in some places of the world, either because it’s chlorinated or very mineral-rich, or it can dilute the fruit flavor. My standard approach is to use parts whole fruit, parts juice, either from the same fruit or something that goes well together. The options are endless and I feel smoothies are a good area for experimenting with flavor combinations. If you feel adventurous and don’t like dairy, you may consider coconut water as liquid, for example.

You can use tea as the liquid. Depending on if you really want to keep the pure mango flavor you can use mango tea but I frequently use regular black tea in my smoothies. Depending on how powerful your blender is you may only need a little in which case adding it hot would be fine. If you need to add more I would suggest waiting for the tea to cool down a little bit.

If you have a garden variety blender, you can first add the mangoes without ice and pulse them a little bit until they're liquid. When you add the ice cubes, there will be enough mango puree to get the cubes twirling.

If you have a strong blender (vitamix class), then you can start without a liquid, it will work well enough without that. You might need to use whatever system the blender provides to get stuff into the blades, mine comes with a special kind of tamper for it. You can also try the pulsing solution from above. In principle, it would be somewhat counterproductive with a strong blender, because these heat up the food and the point of the ice is to cool the fruit from the beginning. In practice, if you start by a few pulses instead of blending it a lot, the mango shouldn't overheat.

As a third option: You mentioned looking for solutions "without adding liquid", but this might be a XY problem, because you do get enough taste as soon as you start adding either flavored liquids or other flavors. Mroll already suggested my favorite solution - add tea - but you can also use fruit juice or the liquid from a compote. Or you could use water and throw in some vanila extract or anything else that you like and that gives you a burst of flavor.