Peel carrots and steam them for 15 up to 20 minutes. They should be cooked but not too soft. Let them cool down.
Thinly slice the carrots using a sharp knife or a broad peeler.
Mix rock salt, flaxseed oil, liquid smoke and lemon juice together in a closable jar or container. Add carrot slices mix well, close and put in the fridge for at least 24 hours up until 48 hours. Make sure to turn and shake the container/jar from time to time to make sure every carrot slice is covered.
Toast the bread slices using a toaster. Spread some vegan ricotta or horseradish mousse onto the toasted slices. Lay carrot slices on top and arrange them like smoked salmon.
Peel onion and cut into rings. Drape some of them on every toastie and add some capers as well. Serve right away.