You get the data for an asset by calling the REST service with the correct parameters in a microflow. For example:
The REST call is to https://gateway.eu1.mindsphere.io/api/iottimeseries/v3/timeseries in this case
The API is documented here: https://documentation.mindsphere.io/MindSphere/apis/iot-iottimeseries/api-iottimeseries-api.html
the URL http://localhost:8080/api/iottimeseries/v3/timeseries/<YOUR_ASSET_ID>/Metrics assumes that you like to fetch data from an asset which have the aspect Metrics. Please replace Metric with the name of your aspect, the aspect name can be found within the Asset Manager of Insights Hub. The generic URL would be http://localhost:8080/api/iottimeseries/v3/timeseries/<YOUR_ASSET_ID>/<YOUR_ASPECT_NAME>
More information about Insights Hub APIs can be found at https://documentation.mindsphere.io/MindSphere/apis/index.html for IOT raw values please see https://documentation.mindsphere.io/MindSphere/apis/iot-iottimeseries/api-iottimeseries-overview.html.