Preheat the oven to 220C, fan-forced, for the tortillas (see Kitchen hack). Thinly slice the red and green capsicums. Thinly slice the onion. Put the chicken flat on a board, put your hand on top and halve horizontally into fillets.
Step 2 — Pan-fry chicken
Combine the Tex-Mex seasoning and 2 tsp olive oil in a large bowl and season with salt and pepper. Add the chicken and turn to coat. Heat a medium frypan over medium-high heat. Cook the chicken for 2-4 mins each side until browned and cooked through. Remove from the pan, reserving the pan. Cover the chicken with a plate or foil to keep warm.
Step 3 — Warm tortillas
Enclose the tortillas in foil. Put in the oven for 8 mins or until softened and warmed through.
Step 4 — Cook veggies
Meanwhile, heat 2 tsp olive oil in the reserved pan over medium heat. Cook the capsicum and onion, stirring occasionally, for 8 mins or until softened. Add 2 tsp red wine vinegar and 1 tsp sugar and cook, stirring, for 1 min or until the liquid is evaporated. Remove the pan from the heat. Taste, then season with salt and pepper.
Step 5 — Serve up
Thinly slice the chicken. Spread the warm tortillas with the mayonnaise, then top with the chicken and capsicum mixture. Or pile everything onto a platter and bring to the table for everyone to help themselves. Enjoy!
Step 6 — Kitchen hack
Don't fancy turning the oven on? Put the tortillas on a plate, slightly overlapping, and microwave for 30 secs or until warmed through. Or, heat a large frypan over medium-high heat. Warm the tortillas, in batches, for 30 secs each side or until warmed through.