Preparations: 

Chicken burgers:

Pan: Heat oil in a pan and fry the burgers for approx. 4 minutes on each side.
Oven: Pre-heat the oven to 180°. Heat the burgers for approx. 15 minutes.
Fryer: Set the fryer temperature to 180°. Fry the burgers for approx. 4 minutes. 

Tomato salsa: 

Blend onion, garlic and olive oil. Add spices, sugar and vinegar and mix it all together in a pot.
Pour in the canned tomatoes and bring to the boil quickly.
Season with salt, pepper and chopped coriander.

Jalapeño dressing:

Chop the jalapeños finely. 
Mix the mayonnaise and Dijon mustard. 
Add the chopped jalapeños.
Season with salt and pepper. 

Fried onions:

Pre-heat a pot with oil or use a fryer, temperature 170°.
Peal and cut the onions into thine slices. Pour some corn starch into a bowl and  flip the onions.
Fry the coated onion in the pot or the fryer until brown and crispy. 
When done, place them on a paper to dry. Add salt. 

Burger:

Heat the burger buns in the oven or on a toaster.
Grease the bun with jalapeño dressing and assemble the burger with lettuce,
avocado, salsa, burger, dressing and fried onions
Place the last bun on top.