Hi Oscar! You can use fennels for seeds (seasoning) and as vegetables. I didn't know, before writing this message, if there was a word in english to describe exactly the fennels used as vegetables. So i looked at wikipedia. And according to wikipedia:
"The Florence fennel (Foeniculum vulgare Azoricum Group; syn. F. vulgare var. azoricum) is a cultivar group with inflated leaf bases which form a bulb-like structure. It is of cultivated origin, and has a mild anise-like flavour, but is more aromatic and sweeter. Florence fennel plants are smaller than the wild type. Their inflated leaf bases are eaten as a vegetable, both raw and cooked. There are several cultivars of Florence fennel, which is also known by several other names, notably the Italian name finocchio. In North American supermarkets, it is often mislabelled as "anise"."
There is also a picture:
So i assumed that the word to describe fennels as vegetables was "Florence fennels"! Wrong assumption, it seems!
Anyway, this is exactly the kind of fennel you should use. Maybe may seems obvious, but you know, i didn't wanted someone using this:
Regarding proportions: i use a single orange, and a single raw fennel bulb. Ideally you may want it to make 50%/50%, but personal preferences have a role here. Personally, i find that a perfectly ripe orange goes marvellously well with salt, oil and fresh pepper, so i tend to use a bit more orange than fennel, but, as i said, is a matter of preferences. Let me know if you like it.