Argentinean style burgers w/Chimichurri sauce

for 4 good size burgers:
500 g ground beef
1 medium onion (chopped)
2 cloves garlic (chopped)
1/2 chill (medium strong, minced)
1 tsp. ground cumin
salt and pepper
splash of grape seed oil

Chimichurri sauce
sliced avocado (1/2 avocado per burger)
sliced red onion (grilled)
hamburger buns (grilled)

Heat a pan to a medium high heat and add splash of oil, then sauté the onion, garlic, chill and cumin until the vegetables soften. Cool slightly.
When the mixture is cooled, add beef , season with salt and pepper and mix well. Form 4 hamburger patties.
Preheat a grilling pan on high heat and add some oil. We like our onion grilled, so first we grill onion. Remove the onion from the pan and add burgers. Grill until cooked. Approximately 4 minutes per side.
Remove from the pan and set aside. In a same pan grill hamburger buns sliced in half.
Serve on grilled hamburger buns with Chimichurri sauce, avocado and grilled onion slices.