If you want a guide to cooking the whole meal in under half an hour, here it is...
Obviously, the time might vary a little depending on a couple of things, but there's really not that much to do, and it can certainly all be cooked in under 20 minutes once you've prepared your ingredients (not naming any names of people with un-realistic cooking times, or anything like that!).
This serves two people, at 409 calories per serving for the salmon, asparagus and cucumber-radish pickles, plus 76 calories if serving with 200g cauliflower rice per person (485 calories in total), or add on 175 calories for a 50g (raw weight) serving of rice. Oh and 3 calories a serving for the spring onion with the rice, if you're counting... ;)
If you're cooking gluten free, use tamari soy sauce, and gluten free miso, e.g. Clearspring's white miso or if you want a darker miso, go for a brown rice version.
[Calories in square brackets if you're counting]
2 boneless, skinless salmon fillets, around 120g each 
2 tbsp mirin (check ingredients for gluten free brands vary) 
2 tbsp soy sauce (preferably Japanese, e.g. Kikkoman - use tamari for gluten free) 
2 tsp sugar (golden caster - or you could substitute honey ) 
1 tsp neutral flavour oil, or a dozen sprays of pure oil from a pump spray (e.g. sunflower, or to suit your diet) 
1 tsp sesame seeds 
(If you want to mix it up a bit, you could also add grated ginger, garlic and chilli to the marinade and include sliced spring onions as an aditional garnish - see notes below)
For the Sesame-Miso Asparagus
200g asparagus, woody ends snapped off 
2 tsp sesame seeds ½ tsp (golden) caster sugar 
½ tsp mirin 
1 tsp sake (or you could substitute Chinese Shaoxing wine, or dry sherry - check ingredients for gluten free cooking as brands vary) 
1 tsp miso paste (for gluten free, use Clearspring organic white miso, or similar - check ingredients) 
For the Cucumber-Radish Pickles100g cucumber (about a third of a whole cucumber) finely sliced 
3 large radishes (about 40g) 
1 tsp lemon juice 
2 tsp rice vinegar (check ingredients if cooking gluten free) 
½ tsp fine sugar (e.g. golden caster) 
For the Rice/Cauliflower Rice
100g easy cook rice (or your favourite) 
400g cauliflower florets 
2 spring onions 
Fill and boil your kettle. Put a medium-sized heavy-based frying pan on a low heat. (Not too large, or when you cook your salmon and add the sauce, the sauce may start to burn around the edges as it evaporates, which will make it taste a little bitter – you want a reasonably snug fit for your contents).
Put the teriyaki marinade ingredients -the mirin, soy and sugar (or honey) - in a non-metallic dish which will snugly contain the salmon fillets (or you could use a sandwich bag), stir to dissolve the sugar a little and put the salmon fillets into marinade, ensuring evenly covered.
If using grain rice, put it on to cook in boiling salted water (for around 15 minutes, but it’s easy cook, so hey – don’t stress – just make a note of the time! If using cauliflower, grate it, or blitz it in the food processor until it resembles small grains, and set aside until the last few minutes), and throw the asparagus in another pan with non-salted boiling water for 3-6 minutes until just tender or griddle it if you prefer (see here for tips on skewering it before griddling etc.). Meanwhile, finely slice the cucumber and radishes (after taking off tops/tails) – easiest and quickest with a mandolin (watch those fingertips!), or in a food processor with fine slicing attachment. Shake salt over the slices, quickly massage through, and set aside in a colander or sieve to drain.
Toast all of the sesame seeds in your heated-up pan until starting to turn golden brown (keep them moving so they don't burn), and remove immediately and set aside. Once cool, you can choose whether to leave them all whole, or to crush 2 tsps of them lightly in a pestle and mortar for the asparagus dressing. I like them both ways, and really couldn't choose!
Make the dressing for the asparagus – put the sugar, mirin, sake, miso paste, and the 2 tsp of sesame seeds in a dish large enough to hold the vegetables and combine thoroughly (a fork, or small whisk is sufficient for this).
Once the asparagus are cooked, immediately toss them in the dressing and set aside (they're good to eat when hot, warm or cool - but not really chilled).
N.B. If you cook the asparagus very lightly and want to serve them hot, you could briefly re-heat just before serving (e.g. by microwaving for 30 seconds to a minute).
Next, take the spring onion, and slice as diagonally and thinly as you can, then give the slices a quick ruffle to separate them. Gently squeeze the cucumber/radish to release any excess liquid and salt (rinse if you want to, but not necessary), add the other ingredients, mix and set aside.
Remove the salmon from the marinade, shaking off any excess and patting dry. Add 2 tbsp water to the marinade and set aside.
Add the oil to the pan, 6 or 7 minutes before the rice is due to finish cooking and put over a medium heat. Swirl the oil around until the pan is hot and evenly coated, then add the salmon steaks top/best side down. Cook until you can see that they are cooked about 1/3 of the way through (where the flesh becomes opaque/light pink - should only take a couple of minutes, but will depend on whether your fillets are thin and tall, or wide and flat) and then turn them over, gently.
Add the reserved marinade to the pan, and continue cooking until the other side is cooked about 1/3 of the way up on the thickest part (the salmon will continue to cook from the residual heat after you've removed it from the pan, and this will give you juicy and moist salmon - but if you're not comfortable with this/slightly 'pink' salmon, then cook a little longer) then remove the salmon (leaving the marinade in the pan) and put on your serving dishes with the pickles, and asparagus.
If cooking cauliflower rice, put it on for two minutes in the microwave (or in a dry, non-stick pan). Meanwhile turn the heat up under your marinade in the pan, until it is bubbling, and reduce until thickened somewhat, swirling in the pan (this won't take long, but be careful it doesn't burn around the edges of your pan, or it will taste bitter) then pour over your salmon steaks, and top with a sprinkling of the toasted sesame seeds, serve up your rice with spring onions scattered over the top and enjoy!
If you want to change the flavour profile a little, and stray from tradition, this is also delicious with some grated ginger (an inch or so) and a clove of crushed garlic added to the marinade, maybe even some sliced or finely chopped red chillies (with or without seeds depending on how hot you like it!), and top with some finely sliced spring onions (scallions) when serving.