In the oven, lay the salami/chorizo slices on kitchen roll, to absorb the released fat. Give them just 30 seconds on your highest setting, then turn the slices over, and repeat the 30 seconds, but be very careful as the slices and run off fat will be extremely hot. From there, go for maybe 10-20 second increments and see how you get along.
My 1100w combi microwave takes about 90 seconds to read-to-eat-ness.
That they can be made on a whim, in under 2 minutes is a bonus and a curse. Hopefully, you'll find a timing that works for you. It's certainly better than paying over £2 a pack in M&S.